Religious belief itself is an adaptation that has evolved because we're hard-wired to form tribalistic religions. Religion is intensely tribalistic. A devout Christian or Muslim doesn't say one religion is as good as another. It gives them faith in the particular group to which they belong and that set of beliefs and moral views.
This is a milder version in this wide-ranging interview of E.O. Wilson in Salon.com (free, but requires viewing an ad).
[Jesse Bering and David Bjorklund's study's] findings are now being cited by other scientists working in an obscure but growing field that seeks to prove a radical notion: that God himself is a product of evolution.
This is a hard-edged version, in this article, almost all of which is devoted to this ambitious thesis. The article, by Julia Reischel, describes an interesting experiment by Bering and Bjorklund, and their results are used to support the audacious claim that god is a product of evolution. As a non-expert outsider, I find the results interesting, but not convincing. However, I like the boldness with which Jesse Bering talks about his research:
... Bering, now a professor in his own right at the University of Arkansas, sounds ready to burn down a cathedral. ... [His] goal is nothing less than to prove to the world, once and for all, that God is a "cognitive illusion" — a figment of our imaginations.
"My meaning in life is to illustrate that there really is no meaning," he says matter-of-factly from his cabin in the Ozark mountains. "I feel that, for the first time in the history of science, we've been able to answer these questions.
"We've got God by the throat, and I'm not going to stop until one of us is dead."
Update: The great folks at Cognitive Daily have a nice post about Bering and Bjorklund's research. There's more interesting stuff -- and links! -- in the comments, too!