Imamate has a broad and comprehensive sense that includes both intellectual authority and political leadership. After the death of the Prophet, the Imam was entrusted with the guardianship of his accomplishments and the continuation of his leadership, in order to teach men the truths of the Qur'an and religion and ordinances concerning society; in short, he was to guide them in all dimensions of their existence.
Such leadership, exercised in its true and proper form, is nothing other than the realization of the goals of Islam and the implementation of its precepts, precepts established by the Messenger of God; it bestows objective existence on the ideal of forming a community and codifying a law for its governance. Imamate and leadership are sometimes understood in a restricted sense to refer to the person who is entrusted with exclusively social or political leadership.
However, the spiritual dimension of man is connected intimately with the mission of religion, and the true and veritable Imam is that exalted person who combines in himself intellectual authority and political leadership; who stands at the head of Islamic society, being enabled thereby both of convey to men the divine laws that exist in every sphere and to implement them; and who preserves the collective identity and the human dignity of the Muslims from decline and corruption.
In addition, the Imam is one whose personality, already in this world, has a divine aspect; his dealings with God and man, his implementation of all the devotional, ethical and social precepts of God's religion, furnish a complete pattern and model for imitation. It is the Imam who guides the movement of men toward perfection. It is therefore incumbent on all believers to follow him in all matters, for he is a living exemplar for the development of the self and of society, and his mode of life is the best specimen of virtue for the Islamic community.
Most Sunni scholars are of the opinion that Caliphate (khilafah) and Imamate (imamah) are synonymous, both signifying the heavy social and political responsibility bestowed on the caliph, who attains his position of guardianship for the affairs of the Muslims by election. The caliph both solves the religious problems of the people and assures public security and guards the frontiers of the country through the exercise of military power. The caliph (or Imam) is therefore at one and the same time a leader of conventional type and a ruler concerned with the welfare of society, whose ultimate aim is the establishment of justice and guarding the frontiers of the country, it is for the sake of these aims that he is elected.
According to this concept, the qualifications for leadership are governmental competence and capacity for rule. On the one hand, the leader must punish errant and corrupt individuals by implementing the penalties God has decreed; hold in check those who would transgress against the rights of others; and repress rebellious and anarchic ruffians.
On the other hand, by acquiring the necessary military equipment and organizing a powerful army, he must both protect the frontiers of the Islamic state against all aggression, and also confront, with jihad and armed struggle, various forms of shirk and corruption and factors of ignorance and unbelief if they prevent the progress or the implementation of true religion and the dissemination of tawhid by way of propagation and guidance powers proves impossible.