In many societies around the world, people attribute illness to supernatural forces, including deities, spirits, and malevolent agents. Using observational data from sub-Saharan Africa and an original large-scale survey in the Democratic Republic of Congo, I show that supernatural beliefs about illness are common and relevant for health behavior: They are associated with higher use of traditional healers, lower use of modern medicine, lower beliefs about the effectiveness of modern medicine, and higher stigma toward those with illness. Then, I conduct a field experiment and ask whether it is possible to shift beliefs and increase the take-up of modern medical treatment. I randomize an informational video about the biomedical origin and treatment of epilepsy, a prevalent disease commonly associated with supernatural forces. The intervention shifts respondents’ beliefs away from supernatural causes and toward modern medicine’s effectiveness for epilepsy as well as for other conditions. The intervention reduces stigma toward those with the disease and increases take-up of free hospital consultations for epilepsy by 50%.

The question of whether religious activities decline with economic development has been actively debated in sociology and economics for centuries. We address this question exploiting house price fluctuations in the U.S. in the early 2000s. We show that an increase in local house prices is associated with a decline in time spent on religious activities for homeowners relative to renters. This effect is not present for volunteering and civic activities. The main result is driven by a wealth effect, whereby activities that have an inferior-good component decline with housing wealth, and by a substitution effect whereby the attractiveness of activities linked to the residential asset increases during housing booms.