Islam in the Ottoman Empire
Islam was the official religion of the Ottoman Empire. The highest position in Islam, "caliphate", was claimed by the sultan, after the defeat of the Mamluks which was established as Ottoman Caliphate. The Sultan was to be a devout Muslim and was given the literal authority of the Caliph. Additionally, Sunni clerics had tremendous influence over government and their authority was central to the regulation of the economy. Despite all this, the Sultan also had a right to decree, enforcing a code called Kanun (law) in Turkish. Additionally, there was a supreme clerical position called the Sheykhulislam ("Sheykh of Islam" in Arabic). Minorities, particularly Christians and Jews but also some others, were mandated to pay the jizya, the poll tax as mandated by traditional Islam.
Atatürk's Reforms
The Ottoman Empire was an Islamic state in which the head of the state, the Sultan, also held the position of Caliph. The social system was organized around the millet structure. The millet structure allowed a great degree of religious, cultural and ethnic continuity across the society but at the same time permitted the religious ideology to be incorporated into the administrative, economic and political system. One can define this way of life as Islamism (Political Islam): "the belief that Islam should guide social and political as well as personal life".