In common with their fellow Muslim believers the Shi’a affirm the Shahada, that is, belief in the unity of God and the model of divine guidance through God’s Messenger, the Prophet Muhammad (peace be upon him). The Shi‘a maintain that for the spiritual and moral guidance of the community, God instructed the Prophet to designate a figure of authority to succeed him as leader of the Muslims. This authority was Imam ‘Ali, the Prophet’s cousin and son-in-law. According to the Shi‘a, this conception of the community’s future leadership was made public by the Prophet in the last year of his life at Ghadir Khumm, where he designated Imam ‘Ali as his successor to lead the Muslims. The specific interpretation of the role of Imam ‘Ali as an authentic leader or ‘Imam of Guidance’ distinguishes the Shi‘a interpretation of authority and leadership from that of other Muslim communities.
The word Shi‘a means ‘partisan’ or ‘adherent’. Specifically, it refers to those Muslims who became followers of ‘Ali, with the conviction that he and his descendants were the rightful authorities of the Muslim Community. For the Shi‘a, this conviction is implicit in the revelation of the Qur’an and the history of Islam, and is not merely the outcome of differences of a purely political nature following the death of the Prophet Muhammad. In order to understand how such an interpretation developed and created a distinctive Shi‘a identity in Muslim history, it is important to see how the Shi‘a ground the concept of guidance within their interpretation of the Holy Qur’an and the life of the Prophet.