But his identity is a question. In the Jewish versions he could have been Elchanan, one of two sons of Rabbi Shimon ben Yitzchak ben Abun of Mainz, a 10th century liturgical poet and an associate of Rabbenu Gershom Me’or HaGolah, “The Light of the Exile”; or maybe the son of Rabbi Shlomo ben Adret (Rashba) of 13th century Spain.
In Christian writings he is sometimes the 12th century antipope Anacletus II, from a Roman family, a descendant of one Baruch, a Jewish convert who became Benedictus Christianus. Anacletus was attacked by his opponents for being of Jewish origin. Another possibility is that he was Gregory VI of the 11th century, formerly John Gratiano, who had Jewish connections. It is also possible that the various stories have been confused and conflated.
The Jewish narratives are built around themes that recur – Jewish children being abducted and brought up as Christians, sometimes reaching high office in the Church, and sometimes returning to their Jewish roots. The main versions were analysed by Dr. Abraham David in an article in “Immanuel”, volume 15 (Winter 1982-83).
Why would a Jewish pope, whoever he was, return to Judaism?
The stories involve the pope’s father coming to Rome, possibly to plead for anti-Jewish measures to be rescinded. Father and son recognise each other; some say the father describes his son’s birthmarks. Playing chess, both know distinctive moves which the father had taught his son. Perhaps they discuss the Bible and the pope offers interpretations which outsiders would not know. In some versions the pope had deliberately imposed restrictions on the Jews, knowing that his father would be sent to Rome to intercede with him. In others the pope, obsessed with his Jewish background, summons his father to explain Judaism.
From the Jewish point of view it is an almost inexorable consequence that the pope becomes Jewish again. One narrative says that he disappears from Rome and returns to Mainz to his father’s house. Another is that, shocked at what he now thinks of as his own perfidy, he decides to perform an act of Kiddush HaShem and commits suicide.
The story could be a straight-out anti-Christian polemic, or a ploy to boost Jewish morale. Since the popular interpretation is that the Jewish pope was the son of Shimon ben Yitzchak ben Abun who was a poet, one can find references in the rabbi’s piyyutim to a tragedy befalling his son Elchanan, and this may be a means of commemorating a tragic ba’al t’shuvah.