Those who are willing to do anything to gain power are capable of using anything, including religion, as a pretext for brutality. History is filled with examples of people claiming to be faithful followers of various religions, including Christianity, doing horrible things in the name of their faith. 

Today the perpetrators are radicalized Muslims, but Islam itself is not the issue. Until we understand that we'll never understand the real problem, which is the social and political situation in the Middle East, of which Islam is one -- but by no means the only -- factor. 

When that kind of instability exists, those who would exploit it for their own political ends take advantage of the situation. It's been that way throughout history and it's no different today.