From the population living in Turkey 99 % are Muslim. The Islam also recognizes Christianity and Judaism. For example Adam, Noah, Abraham, Jesus, Moses and mother Mary and other wise (wo)men and or saints are considered holy to Islam too.

The Koran is the holy Book of the Muslims. The words were revealed to Mohamed and after his death written down in the Kur'an-i Kerim - the holy Koran. It's still the most beautiful, melodic and poetic work in Arabic literature. The Koran is not supposed to be translated and only supposed to be handled after the ritual cleanings. The Koran also provides laws for daily living. This makes the Islam not only a religion but a commonwealth, a theocracy too. There is only the religious law as written in the Koran. In Turkey this is not the case though. The republic of Turkey is a democratic, modern state based on secular values.

The main principles of the Islam are:

• Belief in God and saying so.
• Praying 5 times a day.
• Give alms to the poor.
• Fast during the Ramadan month, if capable of doing so.
• Make a Pilgrimage to Mecca once, if possible.

There are two mainstreams in Turkish Islam, the Sunni and the Alevi. The Alevi are a bit different in case that they are free to pray whenever and where it suits them. They don't have the Friday mosque rituals. The rules are wider in Alevism, which is considered heterodox. Great thinkers like Haci Bektas were Alevi. But in general both streams have their variants of very strict up to just non practicing Muslims.