This is interesting and tbf I am one of those people who do think P(Xtianity|Theism) is high.

But there are many bare theists in the general population! I have a relative with a bumper sticker that says “God is too big for any religion” and this general attitude seems pretty common. I think you see a lot of this attitude among very liberal Xtian clergy who believe in God (probably) and just think of Christianity as a liberal inheritance.

Maybe bare theism isn’t a very motivating position to argue for? no souls at stake?