Wahabism and ISIS roots
The Dönmeh (Turkish: Dönme, Ottoman Turkish: دونمه) were a group of Sabbatean crypto-Jews in the Ottoman Empire who converted publicly to Islam, but retained their beliefs in secret. The movement was centered in Thessaloniki.
The group originated during and soon after the era of Sabbatai Zevi, a 17th-century Jewish rabbi and kabbalist who claimed to be the Jewish Messiah and eventually converted to Islam under threat of death penalty by the Sultan Mehmed IV. After Zevi's conversion, a number of Jews also falsely converted to Islam and became the Dönmeh. Since the 20th century, assimilated Dönmeh have intermarried with other groups and most have assimilated into Turkish society.
The Turkish word dönme is from the verbal root dön- (Ottoman Turkish: دون) that means 'to turn', i.e., "to convert", but in a pejorative sense or 'turncoat'. They are also called Selânikli "person from Thessaloniki" or avdetî "religious convert" (Ottoman Turkish: عودتی). Members of the group refer to themselves as "the Believers" in Hebrew (Hebrew: המאמינים ha-Ma'aminim), or "sazanikos," Turkish for "carp" in reference to the changing outward nature of the fish.
Despite their conversion to Islam, the Sabbateans secretly remained close to Judaism and continued to practice Jewish rituals covertly. They recognized Sabbatai Zevi (1626–1676) as the Jewish Messiah, observed certain commandments with similarities to those in Judaism, and prayed in Hebrew and later in Ladino. They also observed rituals celebrating important events in Zevi's life and interpreted Zevi's conversion in a Kabbalistic way.