In 1666, the Jewish messianic pretender Shabbetai Tsvi was brought before an imperial Ottoman court on charges of sedition. Offered a choice between conversion to Islam and death, he chose the former. Most Jews who had believed in him were quickly disillusioned, but others maintained their faith secretly, viewing his conversion as an act of cosmic redemption, justified through the logic of his antinomian mysticism. While some of these true believers maintained outward conformity to Jewish orthodoxy, others, known as the Dönmeh, followed their leader into the Islamic fold. Cengiz Sisman explains:
After his conversion [to Islam], Shabbetai Tsvi’s worldly and spiritual merit was acknowledged by the Ottomans. He was granted a prestigious name, Aziz Mehmed Efendi. He was clothed in robes of honor and furs and presented with a few purses of silver; he was also granted the honorary position of a gatekeeper, with a royal pension of 150 aspers per day. According to a Dönmeh tradition, several more believers named “İbrahim, Murat, Suleiman, Mahmut, and Yusuf” followed closely in his footsteps. Their wives took the names Zehra, Ayşe, and Melike. Shabbetai Tsvi’s wife Sarah came to Edirne a week after the conversion episode and converted to Islam with the name of Fatima. We are not so sure how many believers followed in the footsteps of the messiah after the conversion event. Until Shabbetai resumed his missionary activity among his former believers two to three years later, the number of Shabbatean converts appears to have remained small.
Exhausted after an arduous conversion experience, Shabbetai Tsvi found himself partaking in a new social and religious world. He lived another ten years that were full of ambiguities and complexities stemming from his new identity as Aziz Mehmet Efendi, which began at the Edirne palace in 1666 and ended in Albania in 1676 as Sabbatai Mehmet Sevi. Interpretations of the conversion and his new identity were fashioned and refashioned during those years, by both himself and his followers. The dialectic between his self-perception and the perceptions of his devotees, his opponents, and the Ottoman authorities caused his identity to oscillate between and across the traditional boundaries of Judaism and Islam, leading to the emergence of a crypto-messianic sect that came to be known as the Dönmeh, who survived until the present day.
Read more on Tablet: http://www.tabletmag.com/jewish-arts-and-culture/220449/sabbatai-sevis-conversion-to-islam