The Day of Atonement (Yom Kippur) was the most important festival of late-antique Judaism, but its influence on Christianity was not generally recognized. Daniel Stökl Ben Ezra here not only reveals the profound influence of Yom Kippur on early Christianity up to the fifth century but also offers the first detailed analysis of the festival itself. He examines the rituals of and the concepts underlying Yom Kippur in various types of Second Temple and rabbinic Judaism. In detailed analyses of many New Testament and extra-canonical writings, as well as Gnostic and early mystical texts, the author portrays the sweeping influence of the high priest, Holy of Holies, blood sacrifice and scapegoat ritual on early Christian thought and practice. In the final part he examines Christian exegesis of Leviticus 16, Christian-Jewish polemics and the impact of Yom Kippur on Christian liturgy.