You're confusing stuff for the readers.

All crusades weren't against Muslims.

It was your Dark Ages, anyway. If Islamic empires could do that, then about any empire across the world could enslave you.

I'd say that's the "Steve Bannon" argument, anyway. Either way, If one hadn't started it the other would have. Religions are a way to gather people together, fill them full of propaganda, and cause them to hate others they would not normally hate. "Men never commit evil so fully and joyfully, as when they do it for religious convictions." Blaise Paskal

One religion will always blame the other as long as they exist with their own "gods". (And the list of that gods "instructions")!