In the early 20th century, contraceptives were illegal and, for many, especially religious groups, taboo. But, in the span of just two years, between 1929 and 1931, many of the United States' most prominent religious groups pronounced contraceptives to be moral and began advocating for the laws restricting them to be repealed. Met with everything from support, to silence, to outright condemnation by other religious groups, these pronouncements and the debates they caused divided the American religious field by an issue of sex and gender for the first time. This article explains why America's religious groups took the positions they did at this crucial moment in history. In doing so, it demonstrates that the politics of sex and gender that divide American religion today is deeply rooted in century-old inequalities of race and class.