It's not the ideologies fault in many cases, it's those individuals that go too far.
Take for example Islam. In my whole life I have only ever met one Muslim who I would say is nasty and evil, and I've met hundreds of Muslims. The fact is that most Muslims are peaceful people who have decent morales and often try to lead by example in a good way. But you get those few nutcases, who only represent 1% of the group, go completely insane. The result is that the 1% of extremist nutcases do stupid things like the September 11th attacks, and they take the limelight and it tarnishes the name of the whole group.
Unfortunately sometimes you get one of those individuals who gains control and starts manipulating the whole organisation and that leads to bad things.
