The problem that we Westerners have is that we don't understand the Muslims very well. If you ask a Muslim about 9/11 the vast majority will condemn it. If you ask the same Muslims about instituting Sharia law in the US they are all for it, in fact they believe it is inevitable.
Probably the biggest hurdle for us to overcome in our thinking is that we don't really believe that Muslims can really believe their religion. They do and it makes them very angry when the world doesn't correspond with their mental map. Muslims don't really consider us equals, more like talking monkeys, until we submit and yet Western society is superior in every way. This causes a disconnect with reality that is expressed in violence. It is truly a mental disorder.