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.
Christianity in the Ottoman Empire
The state's relationship with the Greek Orthodox Church was mixed, since the Orthodox were not killed, they were in the beginning the vast majority and taxpayers, they were encouraged through bribes and exemptions to convert to Islam. In turn they could not proselytize Muslims. The church's structure was kept intact and largely left alone (but under close control and scrutiny) until the Greek War of Independence of 1821–1831 and, later in the 19th and early 20th centuries, during the rise of the Ottoman constitutional monarchy, which was driven to some extent by nationalistic currents. But the Church was greatly affected by the corruption brought in by the Ottoman system of choosing the Patriarch of Constantinople, and putting up the position of Patriarch for bribes. Other churches, like the Serbian Patriarchate of Peć (1766) and Archbishopric of Ohrid (1767), were dissolved and their dioceses placed under the jurisdiction of the Ecumenical Patriarchate of Constantinople. Churches had to be placed in inconspicuous areas, where the everyday populace would not see them.