Among the new political formations of Late Antiquity and the early Middle Ages, the Umayyad Empire is exceptional in the distinctiveness of the new religious tradition that took shape within it. After c. 400 ce, new elites in the Latin West had tended to adopt forms of Christianity as a central component of their political culture, while forms of Christianity and Judaism were also adopted by other new elites elsewhere in North Africa and West Eurasia. As with other late antique military associations, pledged allegiance to a leader was understood in religious terms among the Arabians. While this initially seems to have allowed for some latitude in beliefs and practices among the conquering armies led by the Meccans, boundaries between the new religion and other faith traditions tended to harden over the course of the seventh and eighth centuries. At the same time, conflict within the conquerors, migrants and non-Arabian convert populations generated diverse but distinctively Islamic religious traditions and various Muslim populations who were detached from participation in imperial rule, or active rivals to it.

This chapter examines the impact of these processes on the religious communities of the regions of North Africa and Middle East whom the Arabians encountered when they took power. Because religion had such a central place in political identity in Late Antiquity, it is the primary focus of the chapter, although the category of religion has limits; religious leaders exerted only partial influence over those they claimed to lead, and other markers of difference could have equal or greater significance – among them shared language and culture, economic or class interest, and political and military association. Because Syrian and Egyptian Christianity were the majority religious traditions in the two most important conquered territories for the Umayyads, the chapter begins with the Christian communities in these provinces, before looking at the experiences of the Jews in the same regions, and then smaller groups such as Samaritans. From there, it turns to the rather different context of post-Sasanian Iraq and western Iran where, before the conquests, Christians and Jews had been large minority communities under the rule of Zoroastrians, alongside many other smaller minority religious communities, including Manichaeans and Mandaeans, as well as various Iranian populations who adhered to local forms of Zoroastrianism.