As things currently stand, Islam is uniquely violent among the world religions and a major threat to Western civilization. That is not to say that all or even most Muslims are violent or evil people. It is to say that Islam is an ideological superstructure wherein acts of unspeakable violence can be easily legitimated. To mention but one example, Iran's Mahmoud Ahmadinejad has repeatedly called for the destruction of the state of Israel while in frenzied pursuit of the means thereto. Where do you think he gets his ideas? Why don't Western statesmen make similar demands for the destruction of foreign states?
Islam in the 21st century can be usefully compared to Communism in the 20th. Many intelligent, idealistic, and morally decent people were drawn to Communism in the last century because they believed that in the wake of war and economic depression it was the only way forward for humanity. Whittaker Chambers and Douglas Hyde are two who come readily to mind. (See Communism category.) These decent people, who eventually saw the light, were sucked into a demonic ideology.
There are many decent Muslims. Perhaps there is hope that they can begin to reform and enlighten Islam from within. Here are examples.