I said it often: It's nonsense to say that the 9-11 people "perverted Islam" any more than to say the inquisition "perverted Christianity". We might like to believe it, but the truth is, both Islam and Christianity have side that are very much for such barbarism. It's not a bug, it's a feature.
As you rightly mention, both Christianity and Islam have sides that are for the barbarism in their books. Which, of course, implies that there are sides that are against the barbarism. So rather than using the term 'perverted', let's use the term 'distilled'. The moderates 'distill' an ancient moralistic book through their present morality, and this is true for Christians as well as Muslims.
Those who claim such extremism exist in all religions are correct in theory, but that's not at all the point. The problem isn't the theology per se -- it's that today you'll find virtually no Christians claiming the inquisition is the true Christianity, while you'll find millions of Muslims claiming Al Queda is real Islam.
On the contrary, I think you'll find quite a few Christians who can be quite fundamentalist in the way you mention. Of course, the fact that the Christianity that we come in contact with are in the First World, and hence is balanced by education and affluence, is something that we forget.
If you compare the Muslims in USA to the Christians in USA, you will find that the set of fundamentalist Christians is way more vocal than fundamentalist Muslims. And that is a true comparison, because when you compare, say, a Pakistan to the United States, you are not just comparing Islam to Christianity, but you are also comparing different demographics.
Just like there might be thousands of disenfranchised Muslim extremists in Afghanistan, there were millions of bloodthristy Christians in Rwanda. Sometimes, violence has little do with religion and more to do with economic, social and political crosswinds.
It's pointless to try to explain to them they are not "real" Muslims since they can beat you theologically hands down -- just like Toequemada, for instance, could quote tons of papal bulls supporting his actions. The point is that they are not decent human beings, and if their religion tells them to be such monsters, well, so much the worst for the religion.
You are assuming here that these people commit atrocities ONLY because their religion tells them to. There are no 'real' Muslims and 'fake' Muslims, but only Muslims. This doesn't take away from the fact that the majority of Muslims are not violent. More importantly, if taken in context, accounting for social and economic reasons, Muslims are no more war-mongering than Christians.
Just to put it in context, while the past 10 years has been won by the Muslim terrorists, the decade before that was definitely a victory for the Christian extremists. And if you compare sheer numbers, I think the Lamb of God wins hands down
