The rich in the middle ages used the buying of indulgences as Catholics use confession today. The church has a history of corruption, that’s fine, we’re all humans doing the best we can, hopefully. Morality either lives between your ears or it doesn’t, irrespective of poly, mono, or no deity worship.
Nevertheless, if anybody told them they could buy indulgences instead of repenting and confessing, they were told a lie. In the Middle Ages people got penances like reciting the Penitential Psalms, fasting, and almsgiving. Also ransoming captives, going on pilgrimages, or fighting the Muslims who had invaded and occupied the Holy Land. The Crusades were, in a sense, armed pilgrimages, and often involved indulgences. G'night now, gorush.