This article surveys the emergence and usage of the redefinition of man not as animal rationale (rational animal) but as animal religiosum (religious animal) by numerous English theologians between 1650 and 1700. Across the continuum of English Protestant thought, human nature was being redescribed as unique due to its religious, not primarily its rational, capabilities. This article charts said appearance as a contribution to debates over man's relationship with God; then its subsequent incorporation into the discussion over the theological consequences of arguments in favor of animal rationality, as well as its uses in anti-atheist apologetics; and then the sudden disappearance of the definition of man as animal religiosum at the beginning of the eighteenth century. In doing so, the article hopes to make a useful contribution to our understanding of changing early modern understandings of human nature by reasserting the significance of theological writing in the dispute over the relationship between humans and beasts. As a consequence, it offers a more wide-ranging account of man as animal religiosum than the current focus on “Cambridge Platonism” and “Latitudinarianism” allows.