At the time of the fall of the Western Roman Empire, Christianity had not spread far beyond the cities and towns along the Mediterranean coast. Priests and monks traveled across the Alps to northern Europe as missionaries, converting people to Christianity. Monks began and ended their days and prayer. Some cared for the sick or worked copying religious manuscripts when they weren’t doing missionary work.

the arab empire adopted the muslim religion as their main belief. arabs would influence the people from the territories they invaded towards islam (the muslim belief).

nevertheless, throughout the history of the arab empire, rulers brought intellectual individuals from other religions to their centers of learning. these other foreigners included jews, christians, greeks, persians, and indians.   these resulted in the adoption of important knowledge developed by these cultures by the arabic empire. for example, the works of aristotle were translated from greek to arab and indian scientists brought the numerical concept of "zero" to the arabs.

nowadays, 93% of the arab population is muslim, which at the same time is subdivided in sects including the sunni, zaini, alawi, shia. the remaining 7% is composed mainly of christians.