AHC: Religiously Diverse Middle East

With a PoD of AD 654, have it so that the population of the Middle East (for the purposes of this scenario, North Africa, Arabia, and Persia) are no more than 50% of any individual religion.
 
Maybe have the Umayyads fall apart before the entire region gets Islamised due to some sort of oppression against non-muslims; e.g. outlawing their religion (as long as it inhibits most non-muslims from performing everyday tasks), especially as the population, with a mix of Zoroastrianism, Christianity, Islam, and non-organised religions, could have potentially fulfilled the criteria already, just making it a matter of keeping the situation.

On what level? Broadly, across the entire region you mentioned? Nationally? On a municipal level?

I'm assuming that the 50% is across the whole Middle East.
 
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