Currently, there is no single political or spiritual leader for the worldwide Muslim community. The political unity of Muslims ended with the collapse of the Abbasid caliphate in 1258 as a result of the Mongol invasion. Following the collapse of the Ottoman Empire after World War I, the newly formed Turkish Republic removed the Ottoman Caliphate on the 3^rd of March 1924. The Caliph had represented the spiritual unity of Muslims for many centuries.

The institution of the Caliphate (succession to the Prophet) appeared immediately after the death of Muhammad. It impacted the intellectual, administrative, social and political development of the Muslims throughout their history. The Caliphate is a system in which people manage religious and worldly affairs under the leadership of a Caliph. Initially people elected the first four Caliphs (their total period in office was 30 years). Due to the prevailing circumstances of the time and the norm around the world, the democratic process lapsed back into a leadership by dynasties. This development was predicted by the Prophet Muhammad, who said, "the caliphate is for thirty years. After that will come dynasties."

Although the Caliph was the leader of the universal Muslim State, throughout Muslim history the Muslim world consisted of smaller regional powers and states whose leadership would seek legitimacy and approval from the Caliph. The institution of the Caliphate was used to its full potential to unite and defend the Muslim world by the Ottomans from the 16th century onwards.

The Caliph represented all Muslims but did not interpret religion or bring new changes to it. Religious interpretation lay with the learned scholars and the people themselves. There is no official clergy or institutional body in Islam. Interpretation of religious sources and spiritual leadership are open to any Muslim who appeals to the people, who accepts and acknowledges them by a process of natural selection.

For Sunni Muslims, who form the majority of the followers of Islam, the Caliph or the Imam (leader of Muslims) is elected from among the Muslims on the basis of competence and qualities of leadership. Any leader is fallible. In the Shiite tradition, which makes up about 15% of the total Muslim population in the world, the Imam is the head of Shiite Muslims. He is a pope-like figure who is considered infallible. He should come from the descendants of the Prophet. The Imam leads people through a group of men with titles such as Mullah, Ayatollah (the sign of God) and Hojatulislam (the proof of Islam). Ayatollah Khomeini, who led the 1978 Iranian Revolution, attained the highest spiritual rank within the Shiite clergy and was considered infallible.

Sunni Muslims do not recognise the Ayatollah as their leader. Hence, the ruling (or fatwa) of an Ayatollah only has a bearing of influence on the minority (15%) Shiite population. The religious establishment of Iran appoints the Ayatollah without an election.