Dualism was deeply rooted in the East and did not confine itself to Christianity. In fact the term Manichaean, the name some medieval French chroniclers gave to the Cathars, was used by the Byzantines to describe the dualist ideas of Mani, a third-century Persian, who drew on Zoroastrianism, Buddhism and Babylonian Mandaeism, as well as Christianity. And so it was from several sources that dualism made its appearance in Islam. Though dualism is fundamentally incompatible with Islam, which teaches that God is the sole principle and is good, the political unity of the Muslim world had long been in decay, allowing for the manifestation of new religious tendencies.
Just as the Middle East was divided into local dynasties and subject to pressures from the Abbasid caliphate, the Seljuk Turks and the Fatimids of Egypt, not to mention the Byzantines, so it was divided into numerous
Sects. Among the Christians there were the Jacobites, Maronites, Copts and Orthodox, and among the Muslims the Sunnis and numerous heterodox groups that had evolved out of Shiism, among these the Qarmatian, Alawi, Druze and Ismaili movements, which were not only movements of belief but also initiatory secret societies with political aims tending towards the apocalyptic.
The Ismailis continued certain pre-Muslim beliefs, in particular dualism, in which they saw evil not as the absence of good but as part of the essence of both the world and its creator, who in turn may have been an emanation of an ultimate and unknowable God. Like the Gnostics they believed that man possesses slivers of the divine spark which, given possession of the secret knowledge, can reunite man with the unknown God. The Ismailis claimed to possess this knowledge.
But after Zengi’s conquest of Edessa in 1144 and the surrender of Damascus to his son Nur al-Din, the Zengid dynasty imposed Sunni Islam on the entire Muslim population of Syria, driving the Shia sects into inaccessible regions.