The root cause of terrorism is the Koran.
Part of the root cause goes back to Abraham. When God asked him to sacrifice his son, he agreed. And the father's willingness to kill his son on the alter encouraged irrational authority being acceptable. Each Imam isn't a God, but they have authority beyond anything a westerner can imagine. In our cafeteria way of dealing with religion (where everyone picks and chooses the parts of the Bible (or any other religious book) that they want to stress - Muslims chose this part. The part the reinforces blind authority.
By tradition that authority has been transferred to every two bit Mosque idiot. That power has a choke hold on Muslim cultures. It's also the reason they have suicide bombers and we don't. It's culturally supported. (Did you know the place in Mecca where all Muslims must go is the place where Abraham was asked to kill his son?)