This article explores how Christian theology has historically contributed to the modern ideology of Islamophobia. After arguing that contemporary popular and political Islamophobia has its sources in replacement theology, theological supersessionism, anti-Judaism, antisemitism, Christian-Islamic polemics, Orientalism, and modern racism, it seeks to reorient Catholic theology by undoing and unsaying this discursive and political harm. Constructively, the relatively novel genealogy of Islamophobia this article tentatively traces is based on three discursive moves: linking (1) replacement theology/supersessionism with medieval anti-Islamic theology, (2) the latter to Orientalism, and (3) the previous two to Islamophobia. These three discursive moves are possible because they were and remain sustained by supremacist theologies begotten by replacement theology/supersessionism. The article draws from theories of ideology and social imaginaries to recognize that the words, symbols, narratives, and metaphors that constituted a Christian theology of Islam since the seventh-century emergence of the Islamic tradition cannot be subverted merely by forgetting or ignoring them; they cannot be unlearned merely by learning “positive views” of the Islamic religious traditions (from Muslims, scholars, or both); they cannot be undone through a religion-blind, apolitical theology of religions that rejects nothing that is true and holy in religions; finally, they cannot be dismantled even by a Catholic theology of Islam that cherishes specific beliefs and practices in common with Muslims. It concludes by beginning to construct a Catholic theology of interreligious praxis intended to dismantle and disrupt Islamophobia today. This praxis-oriented theology is grounded in a Christian conception of restorative justice and the Catholic sacrament of reconciliation. At the core of this proposal is the assertion that theologies of the past remain the politics of the present. If Catholic theology has shaped the sociopolitical ideology and structure of Islamophobia today, then an anti-Islamophobic Catholic theology must be political; otherwise, it will remain ineffective in undoing the political harm it has produced.