Splinters and Wooden Beams

I would bet large sums of actual money that your paper has far less effect than you anticipate it will. As one who once occupied the precise epistemological niche you're trying to now reach, I can tell you with certainty that your argument (even fully fleshed out) would have utterly failed to move me, and not on account of any special obtuseness of mine.

Not only are there eloquent Catholic philosophers to reassure smart Catholics that NFP occupies a very different ontological niche than other methods of avoiding conception, but they will reject the claim that your formal argument is the essence of the Catholic rationale behind these policies.

Essentially, though, the real problem is that should you succeed, the goalposts will be moved, because the actual reasons why (many intelligent) people believe certain things are not encapsulated by the arguments they explicitly make.

My journey away from theism was characterized by smaller arguments such as these. There was no great leap, just a steady stream of losing faith in doctrines I had been brought up to believe. Creationism went first. Discrimination against homosexuals went next. Shortly after that, I found it impossible to believe in the existence of hell, except perhaps in a sort of Sartrean way. Shortly after that, I found myself rejecting large portions of the Bible, because the deity depicted therein did not live up to my moral standards. At that point I was finally ready to examine the evidence for God's existence, and find it wanting.

I think in the end you will find that there are two things which can work. You must either point out that the beliefs lead to conclusions that are not just inconsistent, but also absurd, or you must point out that the beliefs lead to conclusions that contradict more "core" beliefs, such as "love your neighbor as yourself".

Fred Clark is a liberal, fairly orthodox Christian. He blogs on a variety of subjects, including the birther/TeaParty movement, the deficiencies of creationism ([1] [2]), the strange phenomenon of religious hatred of homosexuals ([3] [4] [5]), and an interesting view on vampires. (He also has an entertaining ongoing series where he rips apart the popular fundie series 'Left Behind', and shows how the writers know nothing of their own religion, let alone how the real world works.)

You could do worse than to look at how he handles this sort of thing, from a religious perspective.

I suspect that this isn't going to have very much effect, since people opposing homosexuality are likely to do so out of a instinctive revulsion and rationalize the reasons afterwards. (Note that there are both religious and atheist homophobes, and both religious and atheist people who have no problem with it.) On the other hand, it might convince a few rare individuals... and if you can prevent even a couple of homophobes from hurting other people, that is definitely something to applaud.

After all, if someone you know is planning to quit her job and move to Alaska because her horoscope told her that Tauruses need more spontaneity, you shouldn't tell her to stay because she's actually an Aries.

This seems just plain wrong. If "winning" is "getting her not to quit and move to Alaska," pointing out this error seems like a very rational approach; I would even call it the most rational obvious solution. You could, then, conceivably use this error to make a greater point about the problems with astrology as a belief system. But if your immediate goal is stopping the move, giving someone who already strongly believes in astrology a lecture on epistemology is not a winning proposition.

I'm surprised by the number of nay-sayers here.

Obviously convincing someone of Atheism is better than convincing them of the acceptability of homosexuality, but that doesn't mean that the latter is bad. The comparison to swaying an Astrology believer (saying they're an Aries, not a Taurus) is not apt; OP's idea is not to trick them using theist arguments, but to point out the intellectual bankruptcy of believing both in tenets A and B. As a few of the others here have pointed out, the way to remove the wooden beam might be by removing it sliver by sliver.

I think a site such as this would offer an excellent resource for Atheists/Agnostics who regularly argue with Christians over this topic; during my own deconversion process, I was greatly aided by the likes of Professor Richard Carrier who did the scholarly work and laid out the arguments for me - it saved me months of time spent researching, reading, and seeking out sources.

One argument, OP, that I hope you address - I heard this from a bartender the other day. "I'm against gay marriage/adoption because a child needs influences from both sexes." A trite, easy to understand response to this would be wonderful (I'm sure everyone here knows the answer, but I'm trusting that knb will be able to write it with eloquent rhetoric).

After all, if someone you know is planning to quit her job and move to Alaska because her horoscope told her that Tauruses need more spontaneity, you shouldn't tell her to stay because she's actually an Aries. You tell her to stay because astrology is provably bogus.

Maybe you should, if you're in a hurry or she's likely to stop listening to you entirely should you assault astrology too directly... (and if she's actually an Aries).

Go find some gay loving Christians and learn how do they reconcile their tolerance with their faith.

Obligatory quote re. your footnote 2:

—Then, said Cranly, you do not intend to become a protestant?

—I said that I had lost the faith, Stephen answered, but not that I had lost self-respect. What kind of liberation would that be to forsake an absurdity which is logical and coherent and to embrace one which is illogical and incoherent?

—James Joyce

If "your religion requires cognitive dissonance!" were a persuasive argument against religion, no one would bother talking about religion.

Less cynically, your argument does not lead to the contradiction you want it to. Two main reasons. First, that's not the reasoning the Catholic Church uses. They go old-school - Leviticus 20:13 reads:

If a man lies with a male as he lies with a woman, both of them have committed an abomination. Homosexuality being immoral is thus not a conclusion so much as a premise. God doesn't get much clearer than calling something an "abomination."

Your argument arguably misses the point by attacking "natural" birth control. The biblical proscription against birth control comes from the (mis)interpretation of the story of Onan, where God kills a man for spilling his seed instead of impregnating his dead brother's wife. In the "rhythm" method, you're not using any artificial intervention to make it such that seed is spilled, and a significant risk of pregnancy in fact remains. By contrast, birth control and condoms cause barrenness and spilling respectively, so they aren't OK. Yes, this argument is making a rather arbitrary distinction, but unless you can squelch that distinction, you don't get the logical necessity you need. A clearer counterargument would be allowing postmenopausal women to marry, or even married post-menopausal women to have sex. Again, though, it's natural; they aren't failing to get pregnant due to their own actions, they're failing because they just can't do it, and if the church wants to claim that as the distinction, it has a consistent system. Stupid and baseless, but consistent.

For better or worse, the basis of lots of beliefs boil down to "My authority figure says X and I trust my authority figure to be right, so I believe X" - and it can end up taking an awful lot of evidence to modify a belief like this. If you say that X is wrong, you're declaring that you're equal to the authority figure - and, as you're obviously not, you're not going to be believed.

(So... html tags don't appear to work in the less wrong comment section. Too tired to find out what DOES work.)

(snort) If you didn't care about the truth value of what you were telling her as much as you cared about getting her to change her behavior, you might very well choose to exert influence on her from within her belief system. It invokes less resistance on her part than does trying to tear apart the structure of something she places so much faith in. Provided you could convince her that she was actually an Aries and that this would somehow negate her reasons for moving, you might have a shorter, less-painful battle on your hands with respect to her plans to move than you would if you had to take on the whole system of astrology - it's history, it's advocates, the famous people who've believed in it, etc.

Mind you, this is only a temporary fix until the next time she wants to do something stupid as a result of what the 'stars' tell her, but if you don't have the time for a full-blown de-bunking/brainwashing, it might behoove you to be able to exert influence from within the target belief system.

Seems clear to me that you deal with the splinters when you run across them.

If you're more concerned with sending the message out rather than getting credit, then multiple psuedonyms tackling different levels of inferential gaps might be a possibility in the internet era.

You can have one psuedonym who is atheist and is targetting the root questions, however people coming to this final level will be relatively few. You might be mostly preaching to the choir here.

You can have another psuedonym of a tolerant religious person who would write a post like the one you are trying to write. You can signal plently over here. You can say that you are a believer and that love is paramount, etc.

Yes, there are contradictions in the teachings of the Catholic and other churches - but using logic to convince people their religion is mistaken does not seem to work very well.

Believers have a deep emotional connection with their religion and (at least as important) a social bond with their co-believers. They are not going to give that up so easily, 'just' because of some logic.