You'll have to clarify. What is the one thing? What book?
I'm not arguing about variations. You can find variations about anything, with any number of people believing anything. I'm arguing on the basis of their scriptural texts, in order to having something static to evaluate rather than just attacking strawmen and guessing what 'most' or 'many' might believe. From the teachings (Koran) and actions/life (Hadith) of Mohammed, it is easy to make the case for terror. From the same of Christ (new testament), it is difficult if not impossible. The fact that some/many Christians live totally unlike Christ, and some/many Muslims totally unlike Mohammed, is quite beside the point. Imaging sending selected terrorists back in time. An ISIS member would be at home with Mohammed and his closest friends/ranking members. An LRA member would have no common ground with the disciples of Christ.
If you're a disenchanted young guy with an axe to grind, it's not hard to get from 'cut off the heads of the unbelievers" of the Koran, to actually doing so. But the same guy has a hard time getting there from "love your enemy, do good to those who hate you".
Could be, but how does this relate to any arguments about doctrine supporting/negating violence?