From the day the Prophet Muhammad began his mission in 610 C.E., inviting his family members to respond to the call of Islam,cAli, the son of Abu Talib, has figured prominently as a pious believer and an ardent supporter and warrior of Islam in the religious history of Islam. There is no doubt in the historicity of cAli as the champion of Islam. The pages of early history of Islam record countless events in whic;h cAli was assigned by the Prophet to undertake one or another important mission connected with the development of the Umma. There is hardly any other figure in the entire history of Islam who compares with cAli in his loyalty to the Prophet and the teachings of Islam. At the-same time, Ali has been at the center of sectarian controversies and political factionalisms in the Muslim community. If one can trust Muslim authors of sectarian development (al-milal wa al-nihal) in Islam, almost every other faction in the community that separated itself from the majority Sunni community (ahl al-sunna wa al-djama'ah) upheld the belief that c c Ali b. Abi Tallb was endowed with some special qualities and supernatural endowments that set him apart from and above all other companions of the Prophet, and hence, most worthy of the leadership, the Imamate, after the Prophet. This chapter is concerned with an examination of the status of cAli in Twelver Shi'ite religious thought in two areas, as expressed by their religious scholars in their writings. The first area is the wilayah ('authority') of cAli alongside God and. the Prophet as a pivot round which religious belief about the love and devotion to cAli developed