The Maghrib presented a more complex religious landscape than Egypt at the time of the Muslim advance. Romanized populations in towns and coastal plains had long adhered to Christianity, while many interior Berber communities retained traditional religions and some mountain populations had adopted Judaism. Earlier sectarian traditions, including Donatism and Circumcellionism, had already expressed opposition to ecclesiastical authority, taxation, and state control.

Kairouan, founded by Uqba ibn Nafi in 50/670, became a military and missionary center, but Arab rule did not immediately produce widespread conversion. In the first phase, some Berber chiefs and clan elders accepted Islam after military defeat as a way of recognizing the sovereignty of new rulers. When Arab armies withdrew or were expelled, communities sometimes returned to their traditional beliefs, producing repeated cycles of nominal submission and reversion.

Arab policy later shifted toward incorporating Berber elites into the Muslim military order. Musa ibn Nusayr selected young men of noble origin from among prisoners, freed them on condition of conversion, and appointed them to senior commands. The conquest of Spain further accelerated this process: many Berbers joined the armies in search of participation and booty, and the first commander named in the passage, Tariq, was himself a Berber.

Political discrimination and heavy taxation encouraged Berber opposition within an Islamic framework. Kharijite doctrines appealed through their egalitarian, elective, puritan, and anti-absolutist principles. Ibadi and Sufrite communities established the imamate of Tahert and the principality of Sijilmasa, while other Berber groups accepted non-Berber Muslim leaders such as Ibn Rustum, Idris, and Ubaydullah when these figures represented an Islamic alternative to foreign domination.

Other Berber responses combined Islamic inspiration with local religious forms. The Barghawata of the Atlantic plain proclaimed Salih ibn Tarif as a prophet, produced a Quran in Berber, and created a ritual and legal code based largely on local customs. Their state survived on the Atlantic littoral until the eleventh century before being subdued by the Almoravids. Elsewhere, the Idrisids helped deepen Islamization in northern Morocco, while Fez became a western center comparable to Kairouan.

By the fourth/tenth century, Islamization was substantially complete across the Maghrib, but it was not absolute. Small Christian and Jewish communities survived in some towns and regions, remote mountain groups retained older beliefs, and the Barghawata remained outside the dominant religious order until later conquest. After the Fatimids destroyed the Kharijite states, surviving Kharijites either withdrew into remote regions or gradually adopted Maliki Islam; the Almoravids later consolidated Maliki Sunni dominance in the western Maghrib.