Like it or not women are soft and slow physical violence. When a guy gets upset because some other guy looked at him wrong, who's the first to try to restrain him? Probably his girlfriend. I am willing to bet you that the level of violence in an area is directly proportional to how the women are treated by the society of that area. It just so happens that Islam is a huge excuse for oppressing women and as such we have people of that religion running around murdering people. Why? Because if the women say anything, which is their nature if allowed to be acted on, they run the risk of being killed for daring to try to control a man. The founder of Islam was married to a powerful woman who had a habit of telling him what to do. Well he didn't like that so he went and pouted in a cave for awhile until he came up with Islam which he used against his wife and all women since. Contrast that to the Bible where an entire chapter of proverbs is dedicated to how awesome it is to have a wife that does everything so you can just sit around all day. So thoughts: does the oppression and resentment of women directly relate to the violent tendancies of the men?
If you are interested, there was an article out there some time ago by a Berkeley Professor, Steven Fish. It's available here: Islam and Authoritarianism. In the article Professor Fish does a nice job exploring the relationship, if any, between Islam and "authoritarian" societal tendencies. He does so quite rigorously, using quantitative, cross-national data and analyses. The article disputes Samuel Huntington's "Clash of Civilization" theme by raising contravening data, and concludes with where you are heading: Fish concludes that the evidence points to the subordination of women as a leading causal variable for authoritarianism in muslim societies, not Islam itself.