This paper examines a remarkable document that has escaped critical attention within the vast literature on John Rawls, religion, and liberalism: Rawls's undergraduate thesis, “A Brief Inquiry into the Meaning of Sin and Faith: An Interpretation Based on the Concept of Community” (1942). The thesis shows the extent to which a once regnant version of Protestant theology has retreated into seminaries and divinity schools where it now also meets resistance. Ironically, the young Rawls rejected social contract liberalism for reasons that anticipate many of the claims later made against him by secular and religious critics. The thesis and Rawls's late unpublished remarks on religion and World War II offer a new dimension to his intellectual biography. They show the significance of his humanist response to the moral impossibility of political theology. Moreover, they also reveal a kind of Rawlsian piety marginalized by contemporary debates over religion and liberalism.