Between 300 and 1500 CE, Islam emerged as the dominant religion in the Middle East, particularly following its founding in the 7th century. The rapid expansion of Islamic empires, such as the Umayyad and Abbasid caliphates, led to widespread conversion and the establishment of Islamic culture and governance across the region.
Christianity, on the other hand, was already well established in parts of the Middle East prior to the rise of Islam, particularly in regions like present-day Syria and Palestine, but it saw a decline in influence as Islam spread. While Christianity remained a significant religion throughout this period, especially among certain communities, it was overshadowed by the growth of Islam.
During the Crusades (11th to 13th centuries), Christian forces attempted to reclaim territory in the Holy Land, and the conflict highlighted the enduring influence of Christianity in the region. However, this did not alter the overall dominance of Islam in the Middle East.
In summary, while Christianity had a historical presence and influence, Islam became the predominant religion in the Middle East between 300 and 1500 CE.