Seems to me that a lot of this discord has two bases. One is the push for power by individuals or groups and the other is the fear of anyone who appears to be 'different'. Put those two together and there really is the formula for violence.

There also seems to be an aggresive streak inherent in humans, which tends to show itself more in young men than elsewhere in the population. Just look at the violence in football and city gangs. While females do get involved this is a predominantly male activity. Maybe a lot of young males need an outlet for whatever hormonal activity might cause this tendency. Most probably get it from hobbies or pursuing a career, but there always seem to be those who channel it into violence, making them a good breeding ground for the power hungry.

I would agree that religion is often used as an excuse to beat the hell out of other people, because it is such an emotive issue, relying so much on the faith of the believer. Is it possible that many of those who perpetrate the worst viloence do so because they are not sure enough of their own faith to tolerate the fact that other people might not agree?