I know religion is a popular punching bag around here, but this type of behavior derives more from human nature than religion. We are pack animals and are most comfortable when we are able to form groups. I'm reminded of the short story by Dr. Seuss called "
The Sneetches". People will always find some reason to feel they are better than others, even if that reason is completely ridiculous, and that sometimes leads to hostilities.
Of course, your feeling of superiority to anyone who is religious is not in any way related.
:)