Caliph and Imam

Different definitions for the terms Imam, Caliph and Sultanhave been presented by religious scholars from different theological and jurisprudential schools. At the early and the middle ages of Islam, the caliph and Imam were religious concepts and had a mostly political function. These concepts were also used by Muslims after the Prophet death (peace be upon him and his family) for the political rulers. Efforts to define these concepts and determine their instances have led to great controversies. This research tries to answer by a historical-analytical approach the question that, in the interval between the time of the Prophet death and the fall of Abbasid caliphate, in the Islamic society, what the meaningful relationship between the two concepts of the caliph and the Imam was, and historically what changes in these two terms were occurred. The research hypothesis is that these two concepts initially had the same meaning but gradually, by introducing these words into theological, political, and religious conflicts, changes in their meaning were occurred.