The caliphate and succession to the Prophet Muhammad since his decease has been a fundamental point of contention among the Muslims and this contention is still a subject of considerable debate. In other words, the main contention between Shiite Muslims and non-Shiite is on the issue of the nomination of Imam by the Prophet. In café of the main claim of Shiites is that Imam is nominated by God. But the main claim non-Shiites including Ibn Abi al-Hadid have ignored the Shiites' claim that Imam is nominated by God and only supposed that Imam is only the political leader of the Muslim community and it is denying the nomination of Imam Ali (The 1st Shiite Imam) by the Prophet (Muhammad) and proving the legitimacy of the caliphate of caliphs while the Shiite speculative theologians in an defensive approach have centered their attempts on proving the nomination and caliphate of Imam Ali (The 1st Shiite Imam) by the Prophet and proving the illegitimacy of the caliphate of caliphs. So, in this research, in addition to criticizing Ibn Abi al-Hadid's views on the basis of Imam Ali's speeches in Nahj al-Balagha, the emphasis is made on the fact that Imam is primarily the religious leader of the Muslim community and subsequently the political leader of the Muslim community. The main claim of the Prophet's household was not the fact that Imam was nominated by the Prophet but their main claim is the nomination of Imam by God (political leadership of the Muslim community) is of its subsequent and minor aspects. Although neglecting the reality of nomination of Imam (Whose obedience is a religious duty) by God in case of disputing with non-Shiite Muslims is negligible but in presenting Imam to the Shiite Muslims is not acceptable.
Key Words: Imamate (Religious Leadership of the Muslim Community), Caliphate (Political Leadership of the Muslim Community), nomination of Imam by the Prophet (Muhammad), nomination of Imam by God, Imam Amir al-Mu’minin, Abi al-Hadid.