The web site http://scienceblogs.com/pharyngula/2009/04/religion_as_byproduct_of_usefu.php has approximately an hour long presentation on how religious beliefs evolved. It turns out that organized religion is sort of like a parasite.
The web page includes some interesting claims, suchas this:
"Morality is doing what is right regardless of whatwe are told.
"Religious dogma is doing what we are told, no matterwhat is right."
The idea that somehow organized religion has improved our moral values is one of the ultimate unsupported assertions.