Between 1940 and 1944, sociologist Talcott Parsons and political scientist Eric Voegelin engaged in a vigorous correspondence, discussing the origins of totalitarianism and modern anti-Semitism, the legacy of Max Weber, patterns of secularization set in motion by the Protestant Reformation, the methodology and goals of social science, and more. This article introduces and explicates the surprisingly amicable and intellectually rich exchange between these two seemingly different thinkers. Although the letters hold obvious historical interest, their variegated topics are also closely thematically related, revealing an inner logic that we interpret as a theoretical search for “critical naïveté”. This logic, we argue, is relevant to contemporary discussions about the social, political, and scientific legacies of world-transcendent spiritual traditions.