Your Challenge:
With a POD no earlier than the conquest of Sassanid Persia by the Muslim Caliphate, create a Middle East (for sake of argument, the land stretching from OTL Egypt in the West to the Eastern border of Iran) in which no religion has a distinct majority. Although certain faiths may come to be associated with regional leaders, no state becomes truly religiously homogeneous, and has to deal with major religious minorities within its borders.