In his book Darwin's Cathedral, David Sloan Wilson, professor of biology and anthropology at Binghamton University in New York state, says that religiosity emerged as a "useful" genetic trait because it had the effect of making social groups more unified. The communal nature of religion certainly would have given groups of hunter-gatherers a stronger sense of togetherness. This produced a leaner, meaner survival machine, a group that was more likely to be able to defend a waterhole, or kill more antelope, or capture their opponents' daughters. The better the religion was at producing an organised and disciplined group, the more effective they would have been at staying alive, and hence at passing their genes on to the next generation. This is what we mean by "natural selection": adaptations which help survival and reproduction get passed down through the genes. Taking into account the additional suggestion, from various studies of twins, that we may have an inherited disposition towards religious belief, is there any evidence that the Divine Idea might be carried in our genes?

I was recently discussing the need for one to have faith and this article is interesting look at the topic.