What does it mean to belong to, then abandon, and then return to a community? On Wednesday, Feb. 10, 2021, over 500 people who had registered on Zoom had the pleasure and privilege of hearing Dr. Ari Berman, President of Yeshiva University, and Dr. Ephraim Kanarfogel, E. Billi Ivry University Professor of Jewish History, Literature, and Law at the Bernard Revel Graduate School of Jewish Studies, discourse about Dr. Kanarfogel’s newest book, Brothers from Afar: Rabbinic Approaches to Apostasy and Reversion in Medieval Europe, which challenges a long-held view that those who had apostatized and later returned to the Jewish community in northern medieval Europe were encouraged to resume their places without the need for a ceremony or act that verified their reversion.     The event, sponsored by Revel, began with a spirited welcome by Rabbi Yaakov Glasser, David Mitzner Dean of the Center for the Jewish Future. He marveled at how the “medium of Zoom” allowed Yeshiva University to share “this stimulating and elevating experience of scholarship and reflection with people from all over the world,” a point echoed by Dr. Daniel Rynhold, dean of Revel, as Dr. Rynhold set the stage for the two men’s conversation. The next hour was filled with detailed and nuanced investigations of what Dr. Berman called the central issue not only of Dr. Kanarfogel’s work but of Jewish life itself: Jewish identity. “We’ve long been taught the premise that once a Jew, always a Jew: you always stay Jewish and always in all matters,” noted Dr. Berman. But, as both men knew, “the halachic [Jewish legal] history is actually far more complicated,” especially when it concerned those who had converted to another religion and then wanted to return to Judaism. [For more background on this topic, read this interview with Dr. Kanarfogel.] At the end of the conversation, everyone could agree with Dr. Berman when he said that they had had “a very rich and deep conversation that deals with halachic history, social circumstances and how the rabbis applied the Talmudic text to new situations.” The two men also, as Dr. Berman said, “probably raised more questions than they answered but also enlightened a lot of people with new ideas in halachic history that they perhaps had not known before.” For his part, Dr. Kanarforgel lauded Dr. Berman for his erudition on this topic. “He has written a wonderful work on these ideas and is an expert, too, and everyone should seek out his expertise. I hope we can have a return engagement.” The entire event, noted Dr. Berman, demonstrated “a real merger between the yeshiva and the University.” Listen to the audio of the discussion.