Religion
In Turkey, Muslims constitute 90% of the population. The country's primary religion is Islam. To be more specific, you will notice differences in the forms of Islam practiced. 70% of Muslims, or 90%, follow the Sunni faith. The remaining 20% are divided into several faiths, primarily Alevis, but also less common ideas like Sufi worshipping whirling derviches. The Alevis are a Muslim religious minority who are frequently considered heretics - a "Protestant equivalent" in Islam, if you will. Men are allowed to drink alcohol, women have rights, they do not worship in mosques, and the Koran is nothing more than ordinary man's words; as a result, they do not believe in succession. Even if there are no official statistics, estimates state that 15 million Turks are Alevi Muslims.
The whirling derviches are an unusual sight that you will be able to see during your trip to Turkey. Only in Istanbul and Konya will you find followers of this Sufi branch of Islam. Derviches twirl on the tip of their right foot to communicate with God. They can sometimes hold their arms out and rest their heads on their right shoulders for 30 minutes! It's a fascinating and mesmerizing sight, though nowadays it may appear to be more of a tourist attraction than a religious ceremony.