While I have no solid statistics, I would believe in Civilized nations most acts of violence are followed out by people with little or no beliefs. Take Canada for example, you hear of murders all the time in Alberta, mostly in nightclubs, and bars. The majority of murders involves stabbings after a fight or beatings. The large majority of these murders by violence are drug related.

As for religions fighting, I think this is shameful. Another reason why I don't like organized religion but rather follow my own beliefs. This is a problem with organized religion, more often than not, you have a few people making key decisions, and multiples following them blindly. This however is obviously not what the bible intends, but I guess man will try his best to twist anything in their own interests.