firstly,
put 4 males cats in a room, and they will fight, fact.

regardless of where they are from.
lol
and on a serious note, to be honest, I know what your saying.
But wars are caused by other people IMPOSING, their views onto others.
It's not all, peace and love, or, you mind yours, i'll mind mine, because it's an integral part, for them to recruit others.
For example, sorry to use these faiths, but they are the most obvious.
Muslim's only go to their "heaven" if they recruit other people into the faith.
And Jehovah's witnesses and admittadly christians now a days do.
for example, I dont believe in a 6/8 armed blue elephant, but I don't insult it, the problem rest's in all faith's attacking each other, because it's part of that faith.
Christian's are taught god is the only god, others are taught allah. etc etc etc
The problem is the faiths themselves and the followers without enough free will to determine where to bend the rules.