Can I ask for some clarification on this question? By "the turks", do you mean the Turkic peoples as a whole, who historically practiced many religions in different times and places, including Tengrism, Christianity, Zoroastrianism, Manicheanism, etc? Or do you mean the ancestors of the present-day population of Turkey? Or the Oghuz Turks of Transoxiana back to whom Turkish-speaking notables in Anatolia and the Middle East generally traced their ancestry?