Turkey is an overwhelmingly Muslim country. Official figures often put the Muslim share at about 99 per cent, but that number comes from the population registry, which records almost everyone as Muslim by default. Surveys give a more varied picture: roughly 80 to 90 per cent of Turks describe themselves as Muslim, most of them Sunni Muslims of the Hanafi school, while an estimated 10 to 20 per cent are Alevis. Christians and Jews number well under 1 per cent, and a growing minority, especially among young urban Turks, say they are not religious. The state is officially secular under its constitution, yet it runs every mosque in the country through a government body, the Diyanet.
A Land of Many Faiths Before Islam
Anatolia, the peninsula that makes up most of modern Turkey, was one of the heartlands of early Christianity long before it was Muslim. Antioch, now Antakya in southern Turkey, is where the followers of Jesus were first called Christians, according to the Book of Acts. The apostle Paul was born in Tarsus, on Turkey's southern coast, and travelled across Anatolia founding churches, and the seven churches addressed in the Book of Revelation, including Ephesus, Smyrna and Pergamon, were all in western Anatolia. The first seven ecumenical councils of the church, which defined core Christian beliefs, all met in what is now Turkey, including the Council of Nicaea in 325, at the town now called İznik.
Constantinople, today's Istanbul, was the capital of the Christian Byzantine Empire for more than a thousand years. Its great church of Hagia Sophia, completed in 537, was the largest cathedral in the world for nearly a millennium. The rock-cut churches and monasteries of Cappadocia, painted with frescoes between the sixth and thirteenth centuries, are another reminder of that era, described in our guide to Cappadocia and Göreme.
How Anatolia Became Muslim
Turkic peoples, many of whom had converted to Islam in Central Asia, entered Anatolia in force after the Seljuk Turks defeated the Byzantine army at Manzikert in 1071. Over the next four centuries the region slowly became Muslim and Turkish-speaking, through migration, intermarriage and conversion. Sufi mystics played a large part. Jalal al-Din Rumi, the Persian-language poet, settled in Konya in the thirteenth century, and the order founded by his followers, the Mevlevi, became known in the West as the whirling dervishes. Rumi's tomb in Konya is still one of the most visited sites in the country.
In 1453 the Ottoman sultan Mehmed II captured Constantinople and converted Hagia Sophia into a mosque. The Ottomans ruled a huge, religiously mixed empire through the millet system, under which Orthodox Christians, Armenians and Jews ran many of their own religious and legal affairs under their own leaders. From 1517 the Ottoman sultans also claimed the title of caliph, leader of the Muslim world. When Spain expelled its Jews in 1492, Sultan Bayezid II welcomed thousands of them to the empire, and the Sephardic community of Istanbul and Salonica grew from them.
The Loss of the Christian Minorities
At the start of the twentieth century, Christians still made up roughly a fifth of the population of Anatolia. Within a generation almost all of them were gone. During the First World War, in 1915 and 1916, the Ottoman government deported the Armenian population of Anatolia, and somewhere between 600,000 and 1.5 million Armenians died in massacres and death marches, events recognised as genocide by most historians and many countries, though not by Turkey. Assyrian and Greek Christian communities also suffered mass killings. In 1923 Greece and Turkey agreed a compulsory population exchange under which about 1.2 million Orthodox Christians left Anatolia for Greece and around 400,000 Muslims moved the other way, with religion, not language, deciding who went.
Atatürk's Secular Republic
Mustafa Kemal Atatürk, who founded the Turkish Republic in 1923, set out to build a modern, secular state. In 1924 the caliphate was abolished and the religious courts closed, and the Presidency of Religious Affairs, the Diyanet, was created to manage Islam under state control. In 1925 the Sufi orders and their lodges were banned. Islam was removed as the state religion in 1928, the Arabic script was replaced by the Latin alphabet the same year, and from 1932 to 1950 the call to prayer had to be given in Turkish rather than Arabic. In 1934 Hagia Sophia was made a museum. The principle of secularism, laiklik, was written into the constitution in 1937.
Turkish secularism was never a strict separation of religion and state on the American model. It was closer to state control of religion. The Diyanet today employs well over 100,000 people, pays the country's imams, manages more than 85,000 mosques and writes the Friday sermon that is read in mosques nationwide. Its budget is larger than those of many government ministries.
The Alevis
The Alevis are Turkey's largest religious minority, though estimates of their number vary widely, from about 10 to more than 20 per cent of the population. Their faith grew out of Shia Islam and Sufi traditions in Anatolia, reveres Ali, the cousin and son-in-law of the Prophet Muhammad, and has its own practices. Alevis generally do not pray in mosques. They worship in a cemevi, a gathering house, where men and women take part together in the cem ceremony, with music played on the long-necked lute called the bağlama and a ritual dance, the semah. Most do not observe the Ramadan fast in the usual way, and fast instead during the first days of the month of Muharram.
Many Alevis have long supported secular politics, which they see as protection against Sunni dominance. They have also been victims of violence. In July 1993 a mob set fire to a hotel in Sivas where Alevi writers and musicians had gathered for a festival, and 35 people died. The state does not recognise cemevis as places of worship, which means that, unlike mosques, they are not funded by the Diyanet, and Alevi children have had to take compulsory religion classes that teach Sunni Islam, a policy the European Court of Human Rights has criticised.
Religion and Politics Since 2002
Since the Justice and Development Party, the AKP, led by Recep Tayyip Erdoğan, came to power in 2002, religion has become more visible in public life. The long-running ban on women wearing headscarves in universities was relaxed from 2010, and in 2013 it was lifted for most public-sector workers. The number of religious imam hatip schools grew sharply. In 2019 the vast Çamlıca Mosque opened on a hill above the Asian side of Istanbul, the largest in the country. In July 2020 a court annulled the 1934 decree, and Hagia Sophia was reopened as a mosque, a decision welcomed by many Turks and criticised by UNESCO, Greece and many churches. Its history is told in our guide to Hagia Sophia.
At the same time, surveys suggest Turkish society is becoming less religious in some ways. A 2019 survey by the research company Konda found that the share of people describing themselves as non-believers had risen to about 3 per cent from 1 per cent a decade earlier, and that younger Turks were less likely to fast or pray regularly than their parents.
The Religious Year
For most Turks, religion is felt most strongly in the rhythm of the calendar. During Ramadan, called Ramazan in Turkish, drummers still walk the streets of many neighbourhoods before dawn to wake people for the sahur meal, and families and whole districts gather at sunset for the iftar that breaks the fast. The end of the month is celebrated with the three-day Ramazan Bayramı, also called Şeker Bayramı, the "sugar festival", when children go from house to house collecting sweets. About ten weeks later comes Kurban Bayramı, the Feast of the Sacrifice, when families who can afford it sacrifice a sheep or cow and share the meat with neighbours and the poor. Both are national holidays. Most Kurds, who make up perhaps 15 to 20 per cent of the population, are Sunni Muslims too, but they generally follow the Shafi'i school of law rather than the Hanafi school of most Turks.
Christians and Jews Today
The Christian and Jewish communities that remain are small. Estimates suggest there are between 100,000 and 200,000 Christians in total, and the number includes many recent migrants. The largest native group is the Armenian Orthodox community, about 50,000 to 60,000 people, mostly in Istanbul. The Greek Orthodox community of Istanbul, numbering well over 100,000 in the early twentieth century, has fallen to only about 2,000 to 3,000, after the riots of 1955 and expulsions in 1964. Yet Istanbul remains the seat of the Ecumenical Patriarch of Constantinople, considered the "first among equals" by the world's Orthodox churches. The Syriac Christians of the Tur Abdin plateau in the south-east maintain monasteries such as Mor Gabriel, founded in 397 and one of the oldest working monasteries in the world.
Turkey's Jewish community, numbering about 15,000, mostly Sephardic and centred in Istanbul, has also shrunk through emigration to Israel. Its main synagogue, Neve Shalom, was attacked in 1986 and in 2003. Turkey's relationship with its past as a crossroads between faiths is part of its larger question of identity, explored in our article on whether Turkey is in Europe or Asia. In November 2025, marking the 1,700th anniversary of the Council of Nicaea, Pope Leo XIV travelled to İznik to pray with the Ecumenical Patriarch, a reminder of how deep the country's Christian roots run.