Oman is the only country in the world in which the majority of Muslims, at least by the Omani government’s own account, belong to the Ibadi sect of Islam. Ibadism is the only surviving branch of Kharijism, the movement that originated in discontent with the caliphates of ‘Uthman (644–656) and ‘Ali (656–661). Today Ibadis deny that they are Kharijis because of this appellation’s linkage to a long-extinct group that was known for its violence, although there were always moderate Kharijis as well. Ibadism thus represents a third branch of Islam, distinct from Sunnism and Shiism. Ibadis, who number less than 1 percent of the world’s Muslims, are found mainly in the Oman and in small pockets in Algeria, Libya, and Tunisia, and among Omani immigrant communities in East Africa. Sultan Qaboos bin Said was himself an Ibadi. His reign from 1970 to 2020 and his program of modernization and social transformation cannot be fully understood without addressing the role of Ibadism in Omani society and history and the interpretation of Islamic thought fostered under his rule.

The original distinctions between the Kharijis, the Shia, and the main body of Muslims, later called Sunnis, concerned the qualifications of the leader of the Muslims (the caliph/khalifa or imam). Until the end of the ‘Abbasid caliphate (750–1258 CE), Sunnis required that the caliph or imam belong to the Quraysh tribe, but thereafter they accepted any ruler who could unify the majority of Muslims. The Shiites, the partisans of ‘Ali, held that the imam must belong to the immediate household or descendants of Muhammad; the Twelver/Imami and Ismaʻili branches of Shiism hold that there can only be a single true imam, selected by God. Kharijis held that tribe and lineage have no bearing on the qualifications of the imam, who should be selected in consultation with the leading scholars of the community on the basis of his piety and qualifications for leadership.

Among the distinctive features of traditional Ibadism are a strong insistence on just rule, the requirement to resist injustice, and the permissibility of removing tyrannical rulers whenever possible. Unlike Sunni ‘ulama’, who came not only to accept dynastic rule but to make it a religious requirement to obey tyrannical rulers, Ibadi scholars played a role in the selection of the ruling imam and in opposition to injustice.