I am lazy so I will simply copy and paste my response to the other comment.
There was a somewhat peaceful coexistence of all kinds of religions before the collapse of the Ottoman Empire (let’s not get into the genocides the Ottoman Empire committed here). There have been pan-Arab nationalist movements in the 19th century to separate from the Ottoman Empire that the British undermined, see e.g. their meddling in Egypt. There have been local Arab nationalist movements that have been undermined, most prominently the Palestinian one.
Jews were in general safer in the Middle East than in Europe (I hope I don’t have to explain this). Especially in Palestine there have always been Muslims, Christians, and Jews. In Lebanon there were and still are many Christians. In Syria there are many ethnic and religious minorities. In Iraq there has been a coexistence between Shia and Sunni people. Iran wasn’t a very religious country.
The suppression of nationalist movements during the Ottoman period, the arbitrary borders that the British and French drew after they left their colonies, the installment of monarchies loyal to their interests and the creation of Israel all fueled conflicts. After the creation of the apartheid settler colony Israel, the Americans led regime changes in
Syria (1949, 1956-1957)
Egypt (1952)
Iran (1952-1953)
Iraq (1959, 1963)
all with the goal to prevent disloyal governments from forming, or even worse regimes that would take away their rights to extracting resources for free. These regime changes usually led to the establishment of brutal military dictatorships and to resistance groups forming. This is when the religious nut jobs finally entered the stage. They were either fighting the Americans (Iran) or armed by the Americans (Saudi Arabia, Taliban anyone?). And since the post WW2 period sectarian violence emerged because who would have guessed that destabilizing an entire region just to keep its influence down would fuel conflicts between people.
Maybe now you see why it’s such a typical snappy Reddit comment to blame it on religion but it’s in fact a pretty stupid take.
Btw for sources, regarding arab nationalism there’s „10 myths about Israel“ by Ilan Pappe and regarding regime changes there’s an extensive Wikipedia article on all American led regime changes.