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.
Greek Muslims
In Turkey, where most Greek-speaking Muslims live, there are various groups of Grecophone Muslims, some autochthonous, some from parts of present-day Greece and Cyprus who migrated to Turkey under the population exchanges or immigration.
As a rule the Ottomans did not require the Greeks or any non-Islamic group to become Muslims and in fact discouraged it because the dhimmi paid more in tax through the jizya and could be exploited through acts like the devşirme (blood tax) which was one of the organized practices by which the Ottomans took boys from their Christian families, who were later converted to Islam with the aim of selecting and training the ablest of them for leading positions in the Ottoman society. However a large number of Greeks and Slavs became fake Muslims or fake Turks in order to avert the socioeconomic hardships of Ottoman rule. Conversion to Islam is quick and in the Ottoman Empire there were few documents showing who was or was not Muslim, the only requirements were knowing Turkish, saying you were Muslim and possibly getting circumcised. Greek has a specific word for becoming Muslim called "τουρκεύω" and the Slavic languages have turčiti, these practices of fake conversion were common and are a reason so many people in the Balkans have Turkish last names with endings like -oglu. As stated one of the main reason to convert were to avoid paying the jizya a (~ 20%) tax compared to the zakat which was a (~ 3%) tax. Another benefit converts received was that they could no longer be discriminated against in court as the Ottoman Empire had 2 separate court systems in which the Islamic court superseded the non-Islamic court and because non-Muslims were not allowed to be present in the Islamic court that basically resulted in an non-Islamic minority losing in court every time. Conversion allowed those to take advantage of greater employment prospects and possibilities of advancement in the Ottoman government bureaucracy and military. Subsequently, these people became part of the Muslim community of the millet system, which was closely linked to Islamic religious rules. At that time people were bound to their millets by their religious affiliations (or their confessional communities), rather than to their ethnic origins. Muslim communities prospered under the Ottoman Empire, and the Ottoman law did not recognize such notions as ethnicity and the Muslims of any ethnic background enjoyed precisely the same rights and privileges. Another major reason for converting to Islam was the well-organized taxation system based on religion. Major taxes were the Defter and İspençe and the more severe haraç whereby a document was issued which stated that "the holder of this certificate is able to keep his head on the shoulders since he paid the Χαράτσι tax for this year..." All these of course were waived if the person would convert and become Muslim. During the Greek War of Independence, Ottoman Egyptian troops under the leadership of Ibrahim Pasha of Egypt ravaged the island of Crete and the Greek countryside of the Morea where the Muslim Egyptian soldiers enslaved vast numbers of Christian Greek children and women. Ibrahim arranged for the enslaved Greek children to be forcefully converted to Islam "en masse". The enslaved Greeks were subsequently transferred to Egypt where they were sold as slaves. Several decades later in 1843, the English traveler and writer Sir John Gardner Wilkinson described the state of enslaved Greeks who had converted to Islam in Egypt: