This book takes one step further the long-standing debate among scholars of religious antiquity over when and why a parting of the ways happened between Judaism and Christianity in the early centuries of the Common Era. It explores three interrelated questions: what might have happened to prevent that split; how might Western religion have looked had the split not occurred; and how might features of that religion, which never existed, nonetheless manifest in some of the literature and artworks of the past half millennium. The book envisions a religion that stands between historical Judaism and Christianity—a counterfactual construction that challenges Jews and Christians to rethink their actual identities today.