This post was originally going to be titled "Religion sucks", and it was going to include comparisons to nationalism. But I realized after a time that both things are aspects of a more general tribalism.
What is this need of humans to feel that we belong to a group identified by a label, along with feeling that members of different or opposing groups are inferior to ours? It is the latter which is far more pernicious than the former, but they seem to go hand in hand more often than not.
Nationalistic Americans know that their country is the best in the world; all others are inferior, and Americans deserve their lives and livelihoods more than citizens of other countries. Oftentimes, citizens of other countries are considered not quite human.
Some brands of Christians know that they are the only truly saved ones. All others can not -- by definition -- be saved, and the further someone's beliefs are from the believers', well, the less they are to be considered as people worthy of life. Remember how Jerry Falwell (or was it Pat Robertson?) blamed 9/11 on god's anger due to our country turning away from true (Christian) godliness.
Racism is an obvious form of the evil side of tribalism. Fortunately, this is no longer officially sanctioned, but I'm sure we all know far too many people to whom this is second nature.
It even goes so far as fans of sports teams. How often have we heard of brutalities committed which had as their genesis the simple fact of people being fans of opposing teams?
This tribalism seems also to have a component where the failings of the tribe to which a member belongs are minimized or overlooked, while the failings of the opposing tribe are blown all out of proportion. The home tribe is only good, and the other tribe is only evil.
We hear it on talk radio; we read it in online commentary; we listen to it at work and at home. Many people feel this tribalism in themselves, but try to silence that inner voice, with differing levels of success.
I find it all very barbaric. And I despair for humanity's future.