What led to the strengthening, and what to the weakening of the power of the papal authority?

The power of papal authority depended on internal and external factors. After the division of the Christian Church into Catholicism and Orthodoxy, the role of the Pope increased. He dominated Europe and practically rose above secular power. His authority was reinforced by the Inquisition – a church court that destroyed dissent, Protestants and heretics. Also, his power increased during the period of the Crusades. In the 16-17 centuries, its role began to decline, because the number of Protestants and disaffected with the church grew.