The Safavid Empire´s religion was Shi'a Islam and all other religions, and forms of Islam were prohibited.
For over a century the Ottoman Empire and Safavid Persia fought over the control of the South Caucasus and Mesopotamia and dogmatic disputes: the Ottomans were Sunnis and believed the Shia Muslims of the Qizilbash sect were heretics.
Religious differences increased conflict between the two empires because each was composed of a different sect of Islam.
