When the Jewish false messiah Shabbetai Tsvi converted to Islam in 1666—under threat of execution by the Ottoman sultan—most of those who had believed his claims became disillusioned; others remained committed in secret. But his most devoted followers joined him in becoming Muslim, a move they justified through Shabtai’s kabbalistic teachings. Their descendants, known as the Dönme, practice their own idiosyncratic form of Judaism in secret and remain a separate community in modern Turkey, where they are the subject of outlandish, and anti-Semitic, conspiracy theories. Türkay Salim Nefes writes: