I think Islam is a bit more disposed to violence than your average monotheism because of the story trend in its holy book and the history thereafter. In the Torah you have a group that is freed from slavery, grows a nice little kingdom, and then is shithoused by the Babylonians. Jews are accustomed to being the underdog. The Christians get Jesus in their book and Jesus is def. not a warrior. Christianity basically won Rome through a peaceful revolution. It spread until Constantine could no longer afford to outlaw the 25% who embraced it. The Quran is the story of Mohammed's rise to power and not much else. It ends with Islam being as powerful as ever and things only continued to get better for the next 800 years. My small and simple point is that there isn't much humility or nonviolence to be learned from the Quran.
All of that said, being unemployed is a much, MUCH bigger factor in the decision of young men to do terrible things to other people. Religion is just an excuse for that.