Look, my frame of reference is the Balkans, that I know most intimately. There was a time when Greek and Turkish was defined on the basis of religion. You might have been a Turkish speaking Christian in Anatolia or a Greek speaking Muslim in Crete, and you were classified as a Greek and a Turk respectively and forced to migrate accordingly (treaty of Lausanne). In a different part of the Ottoman Empire, in Macedonia, if you sided with the Patriarch of Constantinople you were a Greek, if you sided with the Exarch of Sofia, a Bulgarian. Similarly, ninety years later, a Catholic was declared a Croat, an orthodox a Serb, a Muslim a Bosniac. Look closely and you will see the same story play out in the Caucasus and the East. The genocides of the Armenians, the Pontic Greeks, and the Assyrians by the Ottomans were not motivated by religion but by “national security”.
Religion was used to define who makes up the nations. In the Ottoman Empire, the millet system literally conflated the two ideas. But make no mistake, the Ustashe were not massacring the Serbs because of the Filioque; the Turks did not invade Cyprus in 1974 as part of some Jihad; the Greeks did not invade Anatolia in the 1920s for religious reasons; the Yugoslav wars were not sectarian violence. Religion was not the driver, it was the fuel.
In Lebanon, Syria, Palestine, religion plays a very similar role. Even the sectarian civil wars in Lebanon were mostly about who gets to control what it means to be Lebanese and who gets the upper hand, not about theological differences. Israel was founded by secular Jews as an explicitly national project. Even now, in its interactions with the CUFI crazies, it’s clear to see that the Israelis are willing to put religion aside in the service of the national interest.
Are there people who are primarily driven by religious fanaticism? Of course. But they are treated as weird by the majority. Think for example how almost everyone banded against Daesh.