Effective Altruism vs Missionaries? Advice Requested from a Newly-Built Crowdfunding Platform.

You have a basic foundational difference in your values- if it's showing up in your very first project, it's going to be showing up through the entire lifecycle of the organization. This is a GOOD thing, as learning this now will save you a bloody battle down the road.

Either get out now, and find a way to amicably split your assets, or, if you think I'm overreacting, simply get, in writing, an ironclad agreement that determines what happens if one of you wants to exit. This is standard advice any way for cofounders, and I guarantee you'll thank me later.

saving lives and saving souls are nearly equally important.

If souls actually exist (and could go to heaven and hell) then saving souls is far more important than saving lives! Your disagreement with them is surely not about relative importance, it is about ontology.

How about posting this to the EA forum: http://www.effective-altruism.com/

Someone wrote an introduction to EA for Christians here, not sure if it's any good.

My qualifications to give this advice are nil, but...

Given your differences, I'd think the only way the partnership can possibly work is to focus on creating a neutral platform. That would mean giving up on preferential treatment for effective over religious charities (though you might be able to all agree to penalize political orgs). If your platform becomes what you hope it will, presumably it'll be useful to effective charities without the need for subsidies.

I mean, if you can persuade them to see things your way, that's great, but I don't see it happening.

I strongly believe in effective altruism and they do not. [...] I am being outvoted two-to-one by people who believe saving lives and saving souls are nearly equally important.

Differences in belief about what's important are somewhat independent from differences in disposition about pursuing effectiveness. A person may have very unusual beliefs about what's important (i.e. caring about lives of insects), but remain motivated to seek the most effective ways of influencing these things.

This is the best article on EA and religion that I've seen so far, and uses selective Bible quotes to make points:

https://www.givingwhatwecan.org/blog/2014-12-02/christianity-and-giving

Of course, you can use selective Bible quotes to make nearly any point, so this probably won't work if framed as a counterargument. Perhaps you can just show it to your cofounders and ask what they think, as the beginning of a discussion about what God might want or what Christians owe to non-Christians.

But I second MattG's advice that leaving is probably advisable, particularly if the above goes nowhere.

There are a few partners in the EA community that may be able to help. We have US 501(c)(3) status and likely will charge inline with your arguement (proven effective programs by evidence-based charities are fee-free). Feel free to reach out to me to see what we may be able to help with, randy@charity.is.

So... a large part of what you're doing involves teaching christians how to psychologically manipulate people into donating more money towards converting more people into Christianity?

How likely is it that these two who have the voting control will vote you out of decisions or convert all future efforts into only evangelical efforts?

What percent of future dollars do you think will be spent on purely evangelical efforts and have you fully justified the harm they will/may do by greater benefits elsewhere? (I'm not sure how to calculate the harm of converting someone to a belief system that isn't grounded in reality. I bet someone here has done so before.)