I've agreed that geopolitics Plays a role too. Other side won't concede that the ideology plays a role at all. That seems like me moving to the middle and the other side not willing to budge.
Anyone who does not acknowledge that each of: politics (including geopolitics), structures (economic, class, power, etc.), and religion (Islam, Christianity, Judaism, etc.) all play a role should not be taken seriously. They all do.
How one wants to prioritize and organize those factors is another discussion. I am a big structuralist on this issue, and think that and political institutions explain much of the problem. And, while I think it comes in at a clear third place, religion has historically been violent. At this time, Islam is the "fashionable" violent religion. While I don't believe anything in Islam is inherently more violent than what exists in Christianity, one would be a fool to deny how ISIS, al-Qaeda, et. al are using certain texts within the region to their advantage.
EDIT to say: this is no different than how the very conservative, hassidic Israelis use Judaism to justify violence against Palestinians; or how Christianity has been used for centuries to justify conquest. I.E., I don't think it has anything to do with Islam specifically, but more to do with religion as a whole and the role of religion in the region.