Suppose you ask a religious friend why he doesn’t give up religion, he might say something like “Having faith in God comforts me and I think it is a central part of the human experience. Intellectually I know it’s irrational, but I want to keep my faith anyway. My friends and the government will protect me from making any truly serious mistakes as a result of having too much faith (like falling into dangerous cults or refusing to give medical treatment to my children)."

Um, no. If you were close with that friend, and he proved himself to be pretty intelligent, and he downed a few beers and you kept prying, his answer would be something more like,

"Yeah, I know all that God stuff is a load of garbage, but the public profession of faith in 'God' provides the social glue that allows a welfare-maximizing mutualist group to form, involving people of varying intelligence levels who take this stuff literally and not literally, which grants me access to a large social network with enforcement mechanisms for the prisoner's dilemma, and the ability to trade labor for labor, such as for babysitting, at more favorable rates than cash purchases would allow. Also, it uses psychological mechanisms that allow me to believe strongly enough in my healing to invoke the placebo effect in the body, which gives me real healing. Finally, my price for joining was low enough.

"Show me an atheist group that does all that, and I'm in. *hic* [passes out]."