A commenter over at Trevor's blog asks about Pascal's wager. The standard reply is that it doesn't help you decide which go to believe in and we don't know how impressed by such a cynical motivation for belief.
But in my comment focuses on the problems created by infinite (or Really Big) utilities. Getting to heaven is infinitely valuable, so any probability of getting there is also infinitely valuable and so is any increase in the odds of getting there.
So any activity that increases our chances of getting to heaven is much more important than anything else we ever do. Yet I've yet to meet someone who really organises her life accordingly.
Most people argue that believing in god or being a christian or whatever is enough. But unless they're literally 100% sure that they're going to heaven this response doesn't work. And I guess many people are 100% sure. But that strikes me as really really dumb. I think many people don't understand what it means to be 100% sure...