That some variant of Christianity turns up to be true ? Very, very, very low. Considering the size of the hypothesis space that includes Christianity (it includes about all other religions that ever existed, and most of the fictional ones, and many more you could think about), and the very low amount of evidence, it has to be counted in power of ten. If you consider the core of Christianity to be about 100 bits of information (and that's a very low estimate), and that you have, what, 10 bits of evidence you're left with a probability of 2^-90 of Christianity being true. Those numbers are very imprecise, but if anything, they give a probability higher of what it really is.
That some variant of "theism" is true, including the fact that the universe may be a simulation and the programmers/administrators of the simulation have "godlike" powers in it ? That I would give a much more reasonable chance of being true, but still no real evidence for it, so maybe a 10-20% probability.
That said, I find it really hard to give numbers for my those kind of believes which means... I need to become stronger !
A friend recently asked how strongly I believe that my deconversion from Christianity was not a mistake. Here's my response, and for those of you who are not Christians, I'm just wondering what numbers you would give:
"There is a part of me that wants to say the chance is far less than 1 percent. But when I consider what 1% must mean about my ability to follow complex arguments and base my judgement on the right premises, it seems absurd to say that.
Trying to honestly estimate the chance that I'm wrong about the Bible being generally reliable is a fascinating exercise... I know the number is low, but I'm not sure how low.
Today I would give myself a 1 in 20 chance of being wrong. If I were to consider the arguments of 20 other groups similar to Christian theologians, I would probably misunderstand them at least 1 time in 20. After talking with 20 groups that have a very different worldview, I might think they are all are mistaken, but once in a while, maybe 5% of the time, it would actually be me.
Wow, 5%!?! If I convert that into "There is a 5% probability that the God of the Bible exists and will send me to hell", I feel scared. But I know how to cheer myself up: I just say, "No way, the chance I'll end up in hell MUST be less than 5%. After all, the God of the Bible is CLEARLY just a big, mean alpha-monkey and... [rehearse all the atheistic arguments here]".
This back-and-forth from certainty to uncertainty makes me feel like I'm doing something seriously wrong.
So what about you? What chance do you place on some variant of Christianity turning up to be true, and what chance do you think a god of some sort exists?"
Numbers please.