This article explores the relationship of religion, universal histories of philosophy, and eighteenth-century French vitalism in the work of Abbé Claude Yvon. Yvon, while in exile in the Netherlands, was a high-ranking associate of the Masonic societies of The Hague and close to radical publishers. He was also heralded as a materialist and radical Enlightenment partisan. Upon his return to France in 1762, his significant role in the Prades Affair (1752) led to mistrust and scorn on the part of the French clerical establishment, but he also spent the bulk of his later years writing anti-philosophe apologetics for the Catholic Church. This unlikely collision of seemingly inimical career trajectories makes Yvon a figure that transcends common understandings of Catholic Enlightenment, as well as recent scholarly taxonomies of “radical” and “moderate” Enlightenment introduced by Jonathan Israel's controversial synthesis of the age. Yvon's awkward adherence to a kind of “vitalistic materialism” is but one such aspect of his ambivalent position on the peripheries of radical and Catholic Enlightenment currents.