Current approaches to the history of early modern population thought focus on the state and secular governance, while standard treatments of Restoration and Augustan “political arithmetic” emphasize its economic or social-scientific content. This article recovers nonsecular uses of demographic quantification, excavating the use of political arithmetic in religious polemic between ca. 1660 and ca. 1750. As a form of empirical natural philosophy, political arithmetic suited the polemical needs of latitudinarian Anglicans and others combating deism, atheism, and preadamism; the demographic regularities it revealed furnished evidence of providential solicitude, while the history of population growth was a potential prop for scriptural chronologies. A strand of “sacred” political arithmetic thus contributed to natural theology while modeling—albeit inconsistently—new historical applications for empirical methodology. The article concludes by considering possible causes for the decline of this “sacred” strand of demographic quantification, while suggesting connections between it and better-known secular forms of Enlightenment-era population thought.