It is commonly asserted that heresy is a Christian invention that emerged in late antiquity as Christianity distinguished itself from Judaism. Heresy, Forgery, Novelty probes ancient Jewish disputes regarding religious innovation and argues that Christianity's heresiological impulse is in fact indebted to Jewish precedents. In this book, Jonathan Klawans demonstrates that ancient Jewish literature displays a profound unease regarding religious innovation. The historian Josephus condemned religious innovation outright, and later rabbis valorize the antiquity of their traditions. The Dead Sea sectarians spoke occasionally-and perhaps secretly-of a "new covenant," but more frequently masked newer ideas in rhetorics of renewal or recovery. Other ancient Jews engaged in pseudepigraphy-the false attribution of recent works to prophets of old. The flourishing of such religious forgeries further underscores the dangers associated with religious innovation. As Christianity emerged, the discourse surrounding religious novelty shifted dramatically. On the one hand, Christians came to believe that Jesus had inaugurated a "new covenant," replacing what came prior. On the other hand, Christian writers followed their Jewish predecessors in condemning heretics as dangerous innovators, and concealing new works in pseudepigraphic garb. In its open, unabashed embrace of new things, Christianity parts from Judaism. Christianity's heresiological condemnation of novelty, however, displays continuity with prior Jewish traditions. Heresy, Forgery, Novelty reconsiders and offers a new interpretation of the dynamics of the split between Judaism and Christianity.