Rabbi Menachem Mendel Schneerson was the charismatic leader of the Chabad Hasidic movement and its designated Messiah. Yet when he died in 1994, the messianic fervor he inspired did not subside. Through traditional means and digital technologies, a group of radical Hasidim, the Meshichistim, still keep the Rebbe palpably close-engaging in ongoing dialogue, participating in specific rituals, and developing an ever-expanding visual culture of portraits...