During the 1990s, American evangelical texts contended that men have a stronger sex drive than women and that this natural sexual aggression makes men better suited to leadership roles in marriage, church, and society. Although this theology, called complementarianism, had earlier roots in conservative Protestantism, the connection that evangelicals made between male sexuality and male leadership was influenced by the scientific fields of sociobiology and evolutionary psychology during the 1980s and 1990s. These fields argue that maleness is a genetic evolutionary strategy characterized by social competition and a strong, even aggressive, sex drive. Evangelicals drew upon this scientific model in their efforts to combat second-wave feminism within their communities and in the broader culture. They turned to biology as a defense against the so-called cultural claims of feminism. Significantly, the model that evangelicals drew on from research in sociobiology and evolutionary psychology helped shape the articulations of “natural” masculine behavior in popular Christian self-help books, dating manuals, and theological texts. This article builds on the body of feminist scholarship that has critiqued the evidence, models, and popular influence of sociobiology and evolutionary psychology. But it also urges the importance of analyzing the role of religious practices in the circulation and legitimation of scientific depictions of gender and sexuality.