In this paper I exploit regional variation of Catholicism within France to study the role of religiosity for economic development. Using seven different indicators of religious intensity from 1788 to 1950, I first show that the spatial distribution of religiosity is extremely stable over time. However, when relating religious intensity to several proxies for economic development, I find a strong negative relationship only after 1870 (when the Second Industrial Revolution started and technical skills of the whole workforce began to matter), but not before that date. Using panel data on type of education and different measures of industrialization, I shed light on one possible mechanism and I suggest that schooling was crucial: while after 1850 technical education was being introduced in primary secular schools, the Catholic church played an hindering role, pushing for religious content of schooling -- and the more religious departments started to lag behind.