[hellbender]

Ethnocentrism is inherent in mankind. People like their families best, then their more distant relatives, then other people who look like them and speak the same language and have the same religion. They can easily be convinced to murder and evict people of different race, religion, and language. Look at how Czechoslovakia and Yugoslavia have split up, and rather minor differences between closely related people create dissension in places like Belgium. The idea that you can create a stable nation out of people with radically different races, cultures, and languages without force is a liberal Enlightenment myth. The Roman Empire lasted a few centuries, but the did this by imposing their law with an iron will and "cruel & unusual punishments," as well as settling their colonies with Romans and so thoroughly introducing their language that derivatives of it are spoken all over Europe to this day.

[Elendur]

your are very correct about Ethnocentrism.
and i am not saying a Caliphate would be stable.
(though the Ottoman Empire lasted a LONG time...)

but Islamists will never stop trying. And this could easily result in a major war. Hatred of Israel is their unifier.

also, you correctly noted the power of “...iron will and “cruel & unusual punishments,”” which Islam under Sharia law, certainly qualifies.