Who's hearing what's going on and thinking "supremacy"?
Last I checked, when white people were all up on the whole supremacy thing, a lot of people didn't like it. I would hate to find out what its like to be the victim of that.
The problem with all organized religions, other than the fact they promote wide-scale delusion to rival most documented mental disorders, is that they, like all things created by man, have ambitions to be better than everyone else. This just makes conflict unavoidable.
I'm not saying no god = no war, because I'm not that retarded. But that will at least knock out a major causing factor in almost every single one that's ever happened.