It's not just that it appears to be. There are invocations in the Quran that aren't in the Bible. Certainly not in the New Testament. And these make Islam more susceptible to extremism than Christianity.

Again, yes, all religions are susceptible to extremism. "If you can make people believe absurdities..." and all that. Wars have been fought and atrocities have been committed in the name of most religions. But Islam is particularly susceptible.