Oh... something to do with the crusades. Some Muslims are still pissed off about stuff that happened hundreds or even a couple of thousand of years ago. That's why we should write off the middle east entirely, save our money, and continue to to build nukes and a good missile defense system. Eventually, some two thousand year old beef between Muslims and Jews (or Muslims and someone) will bring us all down. But I'll conceed... our nukes should not have biblical references on them. We should be non- judgmental with weapons of mass salvation.
Islam is 1,388 years old. The European Crusades, a series of
counter-attacks, didn't start until after the Faithful finished overrunning the majority Christian Byzantine Empire in Asia Minor early in the 11th Century.
The beef some Muslims have with the Jews/Israelis in particular (as opposed to anyone not a Muslim in general) is really a 20th Century thing. Don't get caught up in the "eternal, inevitable conflict idea".
The story of militant Islam is really the same old story of an empire's growth, senescence and decay, but that story causes a great deal of anger and disbelief because the empire was founded on perceived religious truth as opposed to a mere political basis. It's a lot easier, in the end, to accept that your political system failed or became outmoded than to believe that reality has proven your fundamental religious beliefs "wrong".