Andreas

Andreas (or Andrew) was the Archbishop of Bari from 1062 to at least 1066, and probably somewhat longer. In 1066, he travelled to Constantinople where at some point he converted to Judaism. mentions his elevation to archbishop in 1062, journey to Constantinople in 1066, and dying in 1078.

Obadiah the Proselyte, another convert to Judaism and émigré to Egypt of about a generation later, was moved and inspired by Andreas's story, and recorded it in his memoirs. In the course of the 20th century, fourteen fragments of the Scroll, now in Budapest, Cambridge and New York, were identified. The fragments in the Kaufmann Genizah Collection, Library of the Hungarian Academy of Sciences, Budapest, were discovered by Alexander Scheiber, the director of the Budapest University of Jewish Studies, who published them in 1954. In one of the fragments, Obadiah tells the story that was widely discussed when he was still Johannes, young son of minor nobility, living with his parents in the small Italian town of Oppido Lucano:

In the Middle Ages only two high-profile cases are known of Catholic clergy converting to Judaism: From the Annals of St. Bertin we learn that in 838 Frankish deacon Bodo converted to Judaism, fled the Aachen court of Louis the Pious, and settled in Muslim Spain. While there, he engaged in a theological debate with Álvaro of Córdoba, Jewish convert to Christianity (some of the letters they exchanged still survive). In De diversitate temporum, Benedictine chronicler Alpert of Metz records the story of Wecelinus, a cleric in the service of Conrad I, Duke of Carinthia, relative of the Holy Roman Emperor Henry II. In the year 1005 or 1006, Wecelinus converted, went to live with the Jews of Mainz, and even publicly polemicized against Christianity; one short tract, preserved by Alpert, enraged the Emperor enough to appoint his own court cleric to refute it. A few years later, in 1012, Henry II expelled all the Jews from the city of Mainz, albeit for a short time.