Imam or leader is the title given to a person who takes the lead in a community in a particular social movement or political ideology or scientific or religious form of thought. Naturally, because of his relation to the people he leads, he must conform his actions to their capabilities in both important and secondary matters.
As is clear from the preceding chapters, the sacred religion of Islam takes into consideration and gives directives concerning all aspects of the life of all men. It investigates human life from the spiritual point of view and guides man accordingly, and it intervenes on the plane of formal and material existence from the point of view of the life of the individual. In the same way it intervenes on the plane of social life and its regulation (i.e., on the plane of government).
Thus the imamate and religious leadership in Islam may be studied from three different perspectives: from the perspective of Islamic government, of Islamic sciences and injunctions, and of leadership and innovative guidance in the spiritual life. Shi'ism believes that since Islamic society is in dire need of guidance in each of these three aspects, the person who occupies the function of giving that guidance and is the leader of the community in these areas of religious concern must be appointed by God and the Prophet. Naturally, the Prophet himself was also appointed by Divine Command.