A few days back I saw a comic strip of a caveman worshipping a rock. A fellow caveman remarked that it was just a stupid rock. The first caveman promply bashed the second caveman's head in (using the rock), saying it was necessary, because he was an 'infidel'.
Now think about it for a second. If we look at the course of history, a lot of wars have been waged in the name of religion. This has been going on over the course of decennia, millennia even.
What if there really is a genetic trait that 'hardwires' us to be religious? What if the holy wars have caused the lesser (read: non) religious genes to be weakened in numbers, or even erradicated? If you look at it like that, religion could have caused a significant change in human evolution.
That would put the whole Evolution vs. Creationism discussion in a whole new perspective, right?