This study examines the reciprocal nature of the relationship between religion and demographic processes in the context of Malawi’s AIDS epidemic between 2001 and 2006. Based on unique data from religious leaders and lay women in rural Malawi, this article shows that religious teachings have been responsive to the demographic realities of AIDS. Predictably, this involves the explicit incorporation of AIDS-related information into teachings on sexual behavior and family formation. More surprisingly, however, Christian and Muslim teachings about marriage and divorce address one of the fundamental problems associated with AIDS: balancing the prevention strategy of leaving a spouse who is putting you at risk of infection with marital, social, and religious obligations to care for the sick. A doctrine of acceptable divorce, “the window of opportunity” reflects an effort to coalesce the sometimes incompatible goals of protecting individuals from HIV, limiting the spread of the disease in the community, maintaining social cohesion, and expanding religious authority. This examination of religious doctrine in the face of a particular demographic crisis illustrates how and why local understandings of demographic phenomena can have profound cultural implications.