The fundamental importance of theology in the work of Carl Schmitt has been the subject of much recent literature on this controversial figure. However, there has been little consensus on the precise nature of Schmitt's own political theology—that is, on what links there are between his religious or metaphysical concepts and his ideas concerning the nature of political organization and action. This is especially the case with his works of the Nazi era, which are now being studied with the same kind of critical attention given to his more influential Weimar works. In this essay I focus on the important turn Schmitt made in the early years of the Third Reich, from “decisionism” to what he called “institutional thinking,” in order to reveal the theological basis for his understanding of the new regime. I will then argue that Schmitt's institutional approach had in fact always been central to his earlier, better-known writings on law and the state. Schmitt's concept of the institution, which had roots in French legal theory, grounded a political theology that was in the end less a metaphysical approach to the state than one that drew on the concrete example of the legal institutional order of the Catholic Church.