This is an excellent talk by Andy Thomson on the biological and psychological origins of religion.
It’s also precisely my position on the matter. There are many people who argue that religion provides a direct evolutionary advantage — I find them unconvincing. Thomson is explaining how religion’s origin is indirect, as a byproduct of properties of the brain that we find useful in modeling our world and social interactions…and religion is a parasite that hijacks these traits to promote a caricature of these properties.
(via Richard Dawkins)