The ethnonym Turks has been commonly used by the non-Muslim Balkan peoples to denote all Muslim settlers in the region, regardless of their ethno-linguistic background. Majority of these, however, were indeed ethnic Turks. In the Ottoman Empire, the Islamic faith was the official religion, with Muslims holding different rights than non-Muslims. Non-Muslim ethno-religious legal groups were identified by different millets. Turk was also notably used to denote all groups in the region who had been Islamized during the Ottoman rule, especially Muslim Albanians and Slavic Muslims. For the Balkan Christians, converting to Islam was synonymous with Turkification, succumbing to "Ottoman rule and embracing the Ottoman way of life," hence "to become a Turk". In South Slavic languages, there are also derivative terms that are more-so seen as offensive towards Bosniaks, such as poturiti, poturčiti and poturica. Slavic Muslims follow the Hanafi school of Sunni Islam, the most dominant school in the Ottoman Empire. According to the religious ideology of Christoslavism, coined by Michael Sells, religion played a key role in maintaining alliances and ethnic identification during tumultuous ethnic conflicts in Southeastern Europe for centuries, from the High Middle Ages onward. Sells postulates that there existed a "belief that Slavs are Christian by nature and that any conversion from Christianity is a betrayal of the Slavic race" as seen in CroatianRoman Catholic and SerbianEastern Orthodox ethnic and nationalist movements. Slavic Muslims were, therefore, not regarded part of their ethnic kinship, as by conversion to Islam, "they have become Turks". In Greece and Greek language, the same belief was held about islamized Greeks, that they had essentially "become Turks", while tourkalvanoi became a common term for Muslim Albanians who had been a significant minority in the country. All of these terms are now considered pejorative ethnic slurs in their respective languages as well as by those groups that they refer to. Following the end of World War I and the dissolution of the Ottoman Empire, all Ottoman Muslims were made part of the modern citizenry or the Turkish nation. While Turkish nationalism viewed all Muslims in Turkey as Turks without exception, non-Muslim minority group, such as Jews and Christians, were designated as "foreign nations", the aforementioned millet. In modern Turkey, data on the ethnic makeup of the country is not officially collected, although various estimates exist. All Muslim citizens are regarded as Turksby law, regardless of their ethnicity or language, in contrast to non-Muslim minorities, which are seen as "non-Turks"; the largest ethnic minority, the Kurds, who are predominantly Muslim and number as many as 15 million, are therefore classified as simply "Turks".
