The story of the renowned scholar of Jewish mysticism Gershom Scholem and his disloyal student Jacob Taubes was one of continuing intellectual quarrel and personal enmity. Their intellectual disagreements centered on Jewish messianism, but the significance of this issue for Taubes’s and Scholem’s thought also reveals a deep intellectual affinity that both were unwilling to face. This article shows how Scholem and Taubes had a surprisingly similar understanding of the nature of messianism, though not its scope. For Scholem, messianism remains a strictly Jewish phenomenon; for Taubes, it is a structural force in the history of Western thought that returns in Jewish, Christian, and even secular phenomena. Nonetheless, for both scholars, messianism was a paradoxical, anarchic, apocalyptic, and revolutionary phenomenon best understood from the perspective of heresy. Focusing on the role of heresy in their interpretation of messianism, this article understands their common theologico-philosophical project as a deconstruction of orthodoxy—or, more precisely, as a deconstruction of the classic dividing line between heresy and orthodoxy.