The faith of Islam spread very swiftly after the death of the Prophet Mohammad in 632 A.D., largely due to three factors. These were, in no certain order, the ease of conversion, the political consolidation of the Islamic state and the remarkable military effectiveness of Islamic armies.
When Islam arrived on the scene in the first millennium A.D., many people in the Arab world and North Africa still practiced pagan faiths, ones that often produced complicated ritualistic and spiritual practices along with social inequality. Islam, on the other hand, provided clear and simple tenets, placed heavy emphasis on social and legal equality, and offered conversion through a profession of faith that was both straightforward and easy to perform. Thus Islam attracted vast numbers of converts from the very beginning. Additionally, originating with the Prophet, Islam embraced the notion of a political reality that incorporated theological principles and moral imperatives based on faith. Consequently, the Islamic state, or Caliphate, spread order, civilization and infrastructure along with the religion. Furthermore, the early Arab armies carrying Islam saw extraordinary military successes in the first decades after the Prophet's death, including conquests of the entire Arab peninsula, much of North Africa, Spain and beyond.