Thwarting a Catholic conversion?

Catholicism of all things

Of the branches of Christianity, and perhaps of all religions, Catholicism has the most developed theology, the most rigorous set of justifications for belief, the longest intellectual tradition and tries the hardest to be convivial with reason. Other branches and other religions would be a lot more surprising (unless you're counting Quakers and Unitarians, for which religion has very little to do with "belief" as we understand it here.) Especially for a self-described virtue ethicist.

My formerly agnostic girlfriend of over 5 years just joined a local Catholic congregation.

The best thing you can do for your friend, is to be a friend. Listen to her and support her as a fellow human being. If you have an agenda for what you want her to be, she will most likely be able to sense this.

Just be her friend and accept her for who she is. If she finds that the Catholic community doesn't accept her wholeheartedly, be there for her. If she finds acceptance there, then accept that too.

Hating people for being wrong is a seductive and tricky thing and can lead to unproductive situations. Limited but generous forgiveness and acceptance are optimal strategies in an imperfect world with imperfect communications channels and fallible actors. (Refer to: Axelrod's Prisoner's Dilemma tournament, and a Tit-For-Two-Tats.)

There's always the possibility she will change her mind again. Ask yourself, would you want to be permanently shunned because you didn't come to the correct conclusion fast enough? What would you think of a community with members that acted in that fashion?

I wonder if anybody has advice on how to handle this

I personally would refrain from publicly criticising her thinking, life choices and core identity on the internet. For example:

But then I remembered how I had been frustrated in the past by her tolerance for what seemed like rank religious bigotry and how often I thought she was taking seriously theological positions that seemed about as likely as the 9/11 attacks being genuinely inspired and ordained by Allah. I remembered how I thought she had a confused conception of meta-ethics and that she often seemed skeptical of reductionism, which in retrospect should have been a major red flag for purported atheists. So yeah, spending all your time arguing about Catholic doctrine really is a warning sign, no matter how strongly you seem to champion the "atheist" side of the debate. Seriously.

... this is insightful and valuable as a warning to others and for your own future reference. But it is more something to do once the victim has already been written off and attempts at influence abandoned.

Maybe it's just me, but the premise of this post rubs me the wrong way. "Thwarting" a conversion? It seems kinda... I don't know. And I'm probably one of the most anti-theistic people that I know or have interacted with on the Internet. It's not like you're trying to prevent her from slipping into alcoholism. As long as she stays fundamentally the same person, I don't see what the big deal is. People should be respected for how they treat others, not what they believe.

That said, I've read a few "convert back to Christianity" stories and a lot of them have similar hidden/leading indicators. There's always some sort of family/significant other factor; it was usually a huge sticking point during their deconversion from religion. I don't really know a lot of this blogger's backstory, but are her family and/or significant other Catholics? That would explain the jump straight from atheism to Catholicism without some sort of intermediary stage (e.g. deism, generic Christianity, etc.) based on my own personal prior probability about how these things happen.

So if that's the case, "thwarting" again seems sort of insensitive. At least to me it would be insensitive language in this context.

To be honest, I doubt that her true rejection matches her stated objections.

For several years, a lot of my friends have been telling me I had an inconsistent and unsustainable philosophy.

Emphasis mine. Her friends are Christian (probably Catholic). They heckle her when she writes atheist material for debates. Her good friend she talks about theology with is a Christian. That's all there is to it.

Humans are still tribal monkeys who follow the customs of their tribe. You put any person around a bunch of Christians (or Buddhists, or Muslims, or Jews), and they'll probably convert. It takes an extremely unusual person to not adopt the religion of their peers, even with all evidence against it.

Nobody says "hmm, according to my understanding of evolutionary theory, group selection wouldn't be a strong enough force to mediate selfish pressures in evolving human moral inclinations, therefore evil is caused by a talking snake." To answer the question directly, you convert any person the same way you change someone's football team, by surrounding them with members of the tribe you want them to be.

Maybe just asking for explanations is the best bet?

"I don't understand the mechanism by which God could make something right or wrong."

"Even if I accept that God must exist, I don't understand where Jesus enters into things"

"If the Catholics have it right, why don't they do any better than the rest of us ethically?"

"The only evidence you have for God is a feeling that morality must have certain properties. What would constitute evidence for or against your views on morality? And if there is no evidence, why believe one way or the other?"

When I first read my friend's post, I had a major "I notice that I am confused" moment, because it just seemed so implausible that someone who understood actual atheist arguments (as opposed to dead little sister Hollywood Atheism) could convert to religion, and Catholicism of all things.

Catholicism is actually one of the intellectually more formidable religions. If you accept a few key axioms of Christianity (and even most atheist Westerners do) and think about their implications for a lot of time it seems remarkable how vulnerable you are to converting to it.

In Christianspace, for the intelectual who likes playing around with very abstract dry concepts Catholicism seems to be a strong attractor. While protestants have played around with reversing its stupidity traditional Western civilization is fundamentally Catholic civilization. It gets the halo effect from a whole lot of art and great thinkers and pretty Churches. Then there is also the sheer majoritarian argument in its favour since it is by far the largest denomination and has institutional continuity going back more than 1500 years. When people around the world think Christianity, they think Catholic.

Also as Moldbug says:

Thomas Aquinas derived Catholicism from pure reason. John Rawls derived progressivism from pure reason. At least one of them must have made a mistake. Maybe they both did. Have you checked their work? One bad variable will bust your whole proof.

Pick a bunch of passages about ethics from several sources - the Bible, the Koran, Buddhist writings, secular writings, etc.

Have her read them, but don't tell her which ones are which. Have her write down her thoughts and feelings about each one, whether she thinks they stand up to logical scrutiny. Then after, tell her the sources of them and ask her whether she might reconsider.

Of course, you'd have to select them carefully so that there are no obvious giveaways (e.g. mentioning God), and also you should be careful not to cherrypick sources that make secularism look good and religion look bad.

I remembered how I thought she had a confused conception of meta-ethics and that she often seemed skeptical of reductionism, which in retrospect should have been a major red flag for purported atheists.

From my view, reductionism is the basic question. If someone is right on evolution but wrong on reductionism, that really doesn't buy them much- and I would wonder how deeply they grasp evolution.

As to how to navigate this: suppose that she has a psychological need to profess a belief in some sort of deity, such that she could not fully thrive without professing that belief. Would you want her to be an atheist then? How can you tell if she has that need or not?

Do people here, in general, think it is productive and worthwhile to spend time and energy on deconverting friends and family (provided the religious beliefs in question are mainstream and not threatening to their physical or financial health)?

That's a genuine question (not rhetoric) in case it wasn't clear.

When I first read my friend's post, I had a major "I notice that I am confused" moment, because it just seemed so implausible that someone who understood actual atheist arguments (as opposed to dead little sister Hollywood Atheism) could convert to religion, and Catholicism of all things.

I'll rejoin Jack and GLaDOS to say that Catholicism isn't the worst of religions. If I was to convert to a religion it would probably be Catholicism, and I've sometimes semi-seriously played with the idea of checking out the local church - and yes, I understand actual atheist arguments, and no, none of my family is pushing me towards religion.

(A significant part of the attraction of Catholicism is being a contrarian for the sake of it, which is not a very good reason. But there's also a good deal of curiosity, and a feeling that they're pretty good at community. On the minus side, they are responsible for a good deal of anti-epistemology, and of course, God doesn't exist.)

But second, and more immediately, I wonder if anybody has advice on how to handle this, or if they've had similar experiences with their friends. I do care about this person, and I was devastated to hear this news, so if there's something I can do to help her, I want to.

Why are you so convinced this is bad for her? Most people are somewhat religious, and every study I've seen suggests they are just as happy, well-adjusted, and moral as non-religious people. I certainly think it is generally better to believe what is true, but is something like this really worth being devastated about? Can't you just be open-minded about her lifestyle choice?

That is very scary. Leah is a pretty well known atheist blogger. It gives me that "there but for the grace of God go I" feeling.

Does she understand the difference between belief and belief in belief? I helped someone escape an unfortunate re-conversion to religion by ensuring they were clear on this distinction, and challenging them on whether they really believed.

I am observing, for more than a three decades now, how a friend of mine, becomes more and more religious. Catholic. When we met, he was a militant leftist atheists. What was quite a norm under communism we had back then here. If not a norm, then something you can easily expect from a young ambitious teenager. Did I say, he was quite a radical anti theist? I was not very comfortable with his rantings against "fools".

Then it started. He insisted on a work free Christmas day, which we had not under the communists. Then he was outraged by my view, that the Socrates was a better man than Christ, what I have only copycat-ed from Russell. Then he started to insist, there is a devil, in his "jokes". Then he rejected Dawkins' Darwinism. Many small steps, toward the God. He is half baked now, I think.

My point is, that the small signs may indeed indicate some "tectonic" shifting inside one's mind. Just as the OP stated.

Whenever I used to hear someone make an argument or profess a belief I considered incorrect, I had the tendency to always try to destroy it right when it came up, because most people will be at least somewhat willing to talk about anything that comes up randomly, but will act like you're being annoying or like you care too much if you try to attack one of their beliefs unprovoked. For example, I would think to myself, "This is my chance. Their religious beliefs may never come up again. I must make use of this opportunity."

But then I realized something. If someone has a belief that really may never come up in conversation again, then it clearly doesn't predict much, or have much of an effect on their practical life, or really anything at all. So for this discussion, the point of this story is that you don't have to attack her religious beliefs directly. If they have any bearing on reality, or on her actual practical life, or anything at all, they'll constantly come up by themselves, and you'll have opportunity after opportunity to destroy them, and not seem like one of those annoying people who always make it their agenda to ram their beliefs down one's throat.

And if they have no bearing on anything, then they're irrelevant anyway, and need not be considered. I've always wondered, what the hell does it mean to "convert" to Catholicism or Christianity or something? Does something about one's person change as a result? Is it like getting a tattoo? Or is it like joining a club? What actually happens as a result? What changes about one's behavior, or one's models of reality, or predictions about what will happen in which situation, or anything like that? It seems rather opaque to me, though of course the answer lies in complex signaling games, or extremely complicated things like why humans have the tendency to think there must be something like "objective morality", rather than just make the ridiculously simple observation that agents have utility functions (or whatever complication you wish to make thereof, to add rigor, such as to take akrasia into account), and that some are different than others.

I guess I'm just saying that it doesn't really matter whether she's "religious" (whatever that means), unless it has a corrosive effect on her behavior in other areas, such as by messing up her practical epistemology and causing her to make worse decisions in her everyday life, or by causing her to think her bisexuality is "wrong" or something. But in any of those cases, it would be best to deal with them directly, and let religion come up only within that context, so as to avoid all the abstract nonsense, and deal with nothing but concrete reality.

From the bit about feeling like morality 'loved' her, she seems to find the prospect that a deity exists to be a good thing -- whether or not it's true, she seems to find the belief more attractive than I think it should be given the evidence.

It might be worth explaining that it would be really cruel for an extremely powerful being to just stand around and watch evolution happen. Or, say, either of the World Wars. So, if somehow we did find out that a deity existed, we would have very strong evidence that it was unfriendly, not to mention unFriendly.

If the above examples don't have an emotional impact, smaller-scale ones might work, such as cruel things that one's seen on the news or some such. Or, if personal experiences are relevant, those might be effective too.

Of course, this doesn't actually address the proposition 'does-the-Catholic-god-exist', but it helps to emotionally frame it more accurately. As far as I know, the really good arguments for atheism tend to be kinda abstract and mathy, and she's likely not to be receptive to, say, wielding Occam's Razor correctly while she's still in love with the idea that a friendly god exists.

One more suggestion: Good and Real proposes a Godless meta-ethics which isn't virtue ethics, but which has parts that might appeal to a virtue ethics fan. So that might be an interesting recommendation.

You asked a question with a real answer, but I think you've asked the wrong question. Setting out with the goal of changing someone is an especially good way to ruin a relationship. It's vastly more essential to learn to value the good in the midst of the bad, because that kind of mixed imperfection is all you will ever find anywhere.

As Catholics are quite specific about, conversion isn't a one-time event. She's in the process of converting, but I've known several people in RCIA who dropped out for one reason or another. And it's sadly true that parish life will give her an unfortunate sense of how bitterly homophobic the hierarchy can be. My sense as a gay convert is that the hierarchy has been using LGBTs as scapegoats for institutional problems in the Church. It is probably the most effective wedge out there to push LGBT people out of the church. That's really your only pressure point that you could push, but you should not stoop to that cruelty.

It's good that you noticed the moment of your confusion! However, the paragraphs you wrote to address that confusion do not provide a correct analysis.

You wrote, "atheists who spend a great deal of their time analyzing and even critiquing the views of a particular religion are at-risk atheists." Taken literally, this is necessarily true because only those who think about a belief can convert to it. But religion-in-general has no content to analyze or critique. It's not possible to convert to religion-in-general, as only particular religions exist. Nobody converts to Thor-worship or pastafarianism; they do convert to major traditions. So the formulation of the problem seems to be designed to obscure the facts rather than express a useful truth. On the more meaningful level, then, the lesson is false -- atheists who spend a great deal of their time analyzing and even critiquing Norse paganism are not at-risk atheists. The appeal to ancient personifications like Zeus/Thor/Osiris/etc or modern mockeries like the FSM is a weak move, substituting a straw man argument when the major traditions of Christianity, Islam, Buddhism, and Hinduism do have iron man arguments out there for those who can engage them.

What you should realize instead from your confusion is exactly what Leah wrote: that, given certain priors, other arguments gain considerable force. So most likely you failed to recognize that force due to having different priors. Don't set out to convert her; set out to reach mutual understanding with her of what her priors were and why.

From a "logical argument" point of view, Vaniver has the right point of view. Reductionism is the key.

From a Dark Arts point of view, reading Leah's post suggests the reason she fell toward Catholicism when she got confused on morality was that she had a bunch of Catholic friends around. Thus being a conspicuously moral (and high-status) atheist will give her an example to fall back to. This isn't too Dark Arts-ish, since you presumably try to be high-status and moral anyway.

It seems, at least, that she understands where the separation of views really occurs:

Based on my in-person arguments to date, it seems like most of my atheist friends disagree two or three steps back from my deciding Morality is actually God. They usually diverge back around the bit where I assert morality, like math, is objective and independent of humans.

As far as Catholicism specifically, she might benefit from reading Elaine Pagels, who discusses at length the historical evidence of the founding of the Catholic Church. Notably, the selection of gospels to include in the New Testament was made specifically to support and cement the authority of the church, not for any well-founded empirical or philosophical reasons.

Catholicism is an organization as well as a belief system, and the organization is terribly, systemically corrupt. An official conversion implies endorsement of the organization as well as the belief system. For a prominent (former) atheist blogger, this seems like a morally questionable act.

But then I remembered how I had been frustrated in the past by her tolerance for what seemed like rank religious bigotry

Could you expend on what you mean by "bigotry", I've seen that word thrown around to shut down debates way too much.

For example, from the above post some might conclude that you are an anti-Catholic bigot, depending on the definition of "bigotry" being used they might well be right.

Jay, I can certainly empathize with your concern for your friend. However, as a practicing Catholic I can assure you that your friend will not be surrounded by people trying to convince her that she needs to "repent" of her sexuality. There's less that I can say about dark side epistemology (since you would probably consider me to be an adherent of it!) but I can assure you that Leah is not going to have piles of nonsensical doctrine shoved down her throat. She will be introduced to many ideas, but ultimately she herself will decide what to accept and what to reject (and I highly doubt that she will accept absolutely everything that the Church teaches - many Catholics don't).

I must confess that, as an outsider to (but occasional reader of) Less Wrong, I find certain statements and arguments on this site to be just as totalizing and dogmatic as the most dangerous religious fundamentalism. There's also a fair amount that I find personally offensive to my value system. However, whenever I find myself going into a nasty tirade against LW, my atheist rationalist friend (who introduced me to this site in the first place) urges me to remember that not all Less Wrongers are the same. Opinions about things like the Singularity vary greatly, as do values. And, there are even some theists on this site.

I can tell you that the same is true about Catholicism. It's a very large organization with many people who interpret their religion in many different ways. Yes, there are many things wrong with the Church as an institution, but people know this and some are trying to reform these flaws (indeed, if Leah does convert, she will be a great one to do this). As for the epistemological side...I don't think that Leah is going to reject scientific truths, if that is what worries you. She might just come to view them in a somewhat different way.

Having read Leah's blog for a while, I know that she will respond very well to any challenge/debate you put forward. However, I would advise against trying to thwart her conversion. Ultimately, she has to make her own decisions. As others have said, listen to her and try your to understand the reasons for her conversion. Also, if you haven't already, get to know a few Catholics. We could be wrong, but that doesn't make us bad people.

During the discussion, he prodded me on where I thought moral law came from in my metaphysics. I talked about morality as though it were some kind of Platonic form, remote from the plane that humans existed on. He wanted to know where the connection was.

I believed that the Moral Law wasn’t just a Platonic truth, abstract and distant. It turns out I actually believed it was some kind of Person, as well as Truth.

Presumably asking her to clarify her belief that Morality = Person, and discussing other options for Morality and why they do not make sense to her as much as the Person one could be a start. Though I'm guessing that it will end up at discussing reductionism, something she is "skeptical of".

Or maybe she just craves more love than she gets, and applying logic is a wrong approach to begin with. Maybe get her to attend one of the more welcoming and less judgmental LW meetups in the area.

EDIT: having looked some more through her blog, she seems (hindsight bias notwithstanding) to have been a closet theists, so this is basically a coming out party for her. You are probably out of luck. Your best (?) bet is that she will run into some hateful zealots who will make her question her beliefs again. Though for her sake I hope that she does not and lives her life as a happy Catholic. Sometimes happiness trumps rationality.

"You don't use your mind to think about religion." - J. R. "Bob" Dobbs, Church of the SubGenius.

The question you asked is how to convince your friend not to become a Catholic. That's the question I'll answer, but it's the wrong question for you to ask.

The Episcopalian faith has much of the content and structure of the Catholic faith, but it is (I hear) more accommodating to women and to non-straight people. Perhaps this might be a better fit for your friend.

The blogger behind ravingatheist.com became a Christian. To his or her credit, the blog remains as it was and the entire record of his or her conversion is there for all to read. This might serve as a guide to you and to your friend, not necessarily in the direction either of you want to go.

If no good can come of or be retained after your friend's conversion, then go ahead and try emotional blackmail. Say 'if you do this I'm not talking to you any more.' If that doesn't feel comfortable, you are starting to ask a better question than how to stop your friend from converting.

Do you know anything about what sort of Catholic she's becoming? There's a wide range within the religion, though I've heard that converts are apt to take the religion more literally.

If she's one of those "there's a real Catholicism, and it isn't the hierarchy" people, then she might not be under as much pressure about her sexuality as you fear.

NOTE ON USAGE: I mean by "theist" only a believer in some sort of god, as opposed to an "atheist."

As far as jumping to Catholicism, even if you ding her on the implausible authoritarianism of infallibility and her apparent disagreement over sexual ethics, all you are arguing for is to move her from Roman Catholic to Anglican.

I personally do not attempt to convert people away from Catholicism or pretty much anything else unless they ask me to or they initiate a discussion with me. I have numerous discussions with my Catholic father, but frankly wonder if I would not be doing a man well into his last 10 years of life a disservice by spending them with his son ridiculing his beliefs.

I would personally skip the Catholicism and Atheism thing. its just more likely to generate bad feeling than any great insights if you approach it as something you have to change about her. Actually, approaching any friend about anything as something you have to change about them is probably more a recipe for pain than for enlightenment, but I suppose reasonable minds might disagree over this.

Also, once you get all nuanced about religion and god and atheism, there isn't that much REAL difference between them, the difference is mostly labeling and signalling. Nuanced atheists believe they can be/are moral, just like theists. Nuanced theists understand that believing there is a deity and knowing details about her and what she wants and what she really thinks and how she really works (and even her gender, if any, for that matter) leaves them hardly better off than an atheist would be anyway at drawing a lot of actionable conclusions from this knowledge. Be gentle and interested in what she believes, and discuss things you genuinely want to discuss with her form that point of view. How she feels about joining such a hierarchical dogmatic religion, but not buying all the dogma. (Really not much harder than being proud to be an American while being against war, pro gay marriage, against slavery and against states' rights.) What is likely the case with intelligent alien races, do they get their own Jesus? Does god likely have different plans for different races? Would there be different moralities for different intelligences or would there be certain common things we can somehow derive from general features of intelligence? A lot of the same questions that were interesting to each of you before her conversion will continue to be interesting afterwards.

Indeed, I would love to talk to a SIAI-cognizant catholic about about simpler issues like cryonics, FAI and UFAI, and whether Jesus/God has visited other alien intelligences and will visit AIs once they establish a culture, or whether God would consider the AI to be such a natural "evolution" of humanity that he would count Jesus' visit as sufficing for both us and our successor species. What is god talking about when she talks about a soul? Can we build a soul, or rather can we build a machine (the brain is still a machine no matter what your religion) that has or gets a soul, or is there some secret miraculous sauce that god has to put in? And even if there is a secret sauce, would you not expect god not to touch any machine that we built that had the capability to support a good soul?

Believing in god doesn't relieve a person from contemplating the deepest mysteries of life and the world. It does not give a person an excuse to fall back to stupidity. The Catholic church includes the Jesuits and many other forces for knowledge and science and rationality in it. Which makes converts to Catholicism every bit as potentially interesting as converts to Atheism or Jews who spend hours a week studying the Talmud. Rather the opposite, it is probably hard to find a Jesuit who would love to go capo a capo against the best we have to offer.

Don't assume you know all that much more than she does. At least not without being willing to check.

"she felt like morality "loved" her."

Maybe you can explain to her that internal constructs can feel like external entities.

also from reading her blog post I got the impression rationality was a limit on her ability to choose her beliefs in this area rather than her means for doing so

"I couldn’t pick consistency over my construction project as long as I didn’t believe it was true."

Also this, "until I discovered that their study of virtue ethics has led them to take a tumble into the Tiber" makes it sound like she is a "pragmatist" or whatever the term is or she thinks finding the true morality has to be satisfying for some reason.

Also I can't believe this doesn't bother people. If you are happy to worship someone who sends people to hell your morality sucks. That your morality isn't currently (directly) harming anyone doesn't mean it's not dangerous.

I don't think the conversion will last.

From what I've heard, the (Catholic, at least) Church view on sexuality is derived mostly from Aristotle.

The world looks pretty scary when we try and look at it as it really is. As much as we try to account for it, at some level we are a function of that which we observe and take in- from that viewpoint, it is not difficult to imagine a scenario where the information you take in becomes skewed along lines that don't mach up with reality. Given enough skewed data, we all make choices that appear irrational from other eyes.

Sadly, none of us rank information told us once as highly as information we "discover" for ourselves. I don't know if the conversion process works like the de-conversion process at all, or if my de-conversion was typical, but the process of moving from an indoctrinated evangelical christian to an out atheist was the work of years, of countless internal dialogues, and of long periods of confusion. In some ways, becoming an atheist meant embracing my confusion- in understanding that clear answers are very rarely present, and even more rarely easy to find. Faced with that, I think I can imagine a process that would sway an atheist mind.

What to do about it? I don't know. Religion provides a certainty, a comfort that atheism seemingly cannot- we cannot right now promise you will live forever, or even longer than the average person with any confidence. We cannot tell you your place in the world, or give you an easy guide to how to live life well. We have half answers, and bits and pieces, and we ask you to take all this uncertainty, and do the best you can with it. That's not an easy way to live life, and I can see how easy it would be to want an escape, into the arms of something more concrete.

Edit: paragraph breaks ahoy!

[Executive summary: solve the underlying causes of your problem by becoming Pope]

I think it's a mistake to focus too much on the case of one particular convert to Catholicism simply because you know her personally. To do that is to fall prey to the availability heuristic.

The root cause of your problem with your friend is that the Catholic Church exists as a powerful and influential organisation which continues to promote its weird dogma, polluting Leah's mind along with millions of others. Before investing time and effort trying to flip her back to the side of reason, you should consider whether you could destroy the Church and dam the river of poison at its source. I will now outline a metho

It probably won't lead to the bottom line she's already seemed to have drawn, but I can share a bunch of material from my ethics class (which is very much science-based, and has a lot of good videos and literature to read). I'm only 1/3 done with the class, but to the degree that it wipes everything away and starts from scratch, I feel that it could only help a person on their journey of understanding ethics.

Let me know if you're interested.

It seems the impetus for her conversion was increasing frustration that she had no good naturalistic account for objective morality in the form of virtue ethics; that upon reflection, she decided she felt like morality "loved" her; that this feeling implied God;

Throw desirism at her?

The fully general argument against supernatural belief is physicalism/reductionism. The fully general argument against omnipotent/omnibenevolent beings in our local space is anti-panglossianism, ie fun theory. Pick one.

That said, when someone starts arguing that it's impossible to derive ought-from-is, and therefore we need God to ground morality, I always want to ask if it isn't a bit suspect that they just derived is-from-ought.

People in general rarely do things for rational, sensible, truth-based reasons. So generally, if I really want someone to do or think something, I manipuate them into it. Of course, this may harm your friendship (if you get caught) or damage the person (if you are not apt at such things) or it may run against your personal ethics. None of these are bad reasons to refrain, but if what you really want is her deconversion, you already want to manipulate her and might as well use effective tools (rhetoric, emotional blackmail, cognitive biases, reputation/shaming... whatever suits you) rather than less effective means such as facts, evidence, or logical reasoning.

Hate to be self-promoting, but I just wrote a blog post on this that you might find useful.

Given that conversions tend to be driven by people's personal connections, probably realistically the best thing you can do to stop something like this (at least in the future) is get someone a good support network of non-believing friends.

Though that's probably not what I'd do in your situation. I'd be screaming at hear that the Catholic church is evil and if she must be religious, why can't she be a nice Episcopalian or something? Which is kinda what I do in my blog post, who knows if she'll follow the blog ping to it.

Um, as a slightly nicer approach that will still get at the "Catholic church is evil" thing, you might try to get her to read William Lobdell's book "Losing My Religion," which talks about how (among other things) being a journalist covering the Catholic sexual abuse scandals led to him leaving the church.

Orthodox Church is strictly more probable than Catholic Church regarding truthness of dogma. ETA: assuming that both probabilities are greater than zero.

I would like your friend not to give money to an organisation that actively shelters child rapists. Refusing to tithe and giving to religious charities is cool, though.

[Executive summary: solve the underlying causes of your problem by becoming Pope]

I think it's a mistake to focus too much on the case of one particular convert to Catholicism simply because you know her personally. To do that is to fall prey to the availability heuristic.

The root cause of your problem with your friend is that the Catholic Church exists as a powerful and influential organisation which continues to promote its weird dogma, polluting Leah's mind along with the minds of millions of others. Before investing time and effort trying to flip her back to the side of reason, you should evaluate the costs and benefits of destroying the Church as an effective entity. I will now outline a method by which you and around 20 like-minded friends could do just that.

The Catholic Church is based in a tiny pseudo-state called Vatican City State. It has no permanent population and no true army, the Swiss Guard being more of a ceremonial bodyguard force (although they do have modern firearms as well as the cool-looking pikes).

What I propose is that you wait until the current Pope dies (not long now!) and a conclave has been assembled, then rush Vatican City in an infantry-style terrorist assault. There are 150 or so of the Swiss Guard but you could divide their forces by having some of you occupy a building, display simulated explosives and make fake demands. Your true targets are the cardinals who are there to elect a new Pope.

Once you capture the cardinals, simply force them at gunpoint to elect you Pope. In the event that you're not already a Bishop and therefore not an eligible candidate for the Papacy, simply mount a privilege escalation attack, whereby you force them to elect you to successively higher offices until you become a valid Pope. I anticipate that this process will be completed before the Italian state can mount an effective special forces operation to kill you.

Now you are Pope, you are the sovereign of the Vatican City State. You can pardon your co-conspirators, and appoint them as ambassadors so they have diplomatic immunity outside VSS. You can then use your papal infallibility to remove all the problematic doctrines of the Church (homophobia, opposition to birth control/abortion, etc.) and bring all the child rapists it has shielded and enabled to justice. Or you could change all Catholic doctrines to those of Pastafarianism. Either way, the appeal of Catholicism to your friend would be destroyed as its so-called timeless moral insights are revealed as human constructs. One or (preferably) more "True" Catholic churches will arise to challenge your claim to the Papacy, causing decades of damaging, hilarious schisms, during which you should make sure to declare several Antipopes.

I suggest you treat this post as if it's a joke, and then seek military training as soon as possible.

Religion is politics. Politics is the mind-killer. Arguably we should discourage overtly political discussion on LessWrong.