What event weakened the catholic church?

Answer 1

Martin Luther's private doubt that the pope had the authority to sell indulgences (paper documents that one could buy to free oneself from a sin) grew into a church debate after Luther nailed 95 theses against the church door in Wittenberg. This practice of displaying an invitation for a scholarly debate was normal at that time, particularly for a professor of theology, which is what Luther was. Luther's reluctance to believe in absolute papal authority was not a singular man's concern: there were numerous other scholars who challenged the grip of the Catholic clergy onto laypersons. Among the educated and/or well-to-do citizens, many felt that the Church was politically too powerful. The zeitgeist smacked of other things: mercantilism, humanism, the stirrings of individuality, a yearning for more freedom. Luther was forced to see the emperor of the Holy Roman Empire, but would not recant. A powerful duke (of Saxony) "kidnapped" Luther on his way home from the meeting with the emperor and hid him in his castle. There Luther translated The Bible into the German language -- breaking a thousand-year-old necessity to have Latin-trained clergy mediate biblical content to laity. Afterward, the people who protested the Catholic Church's monopoly on the relations between God and humans called themselves Lutherans or Protestants. This schism was the single most-weakening event in the Catholic Church.

Answer 2

The church was weakened by internal conflicts as well as by quarrels between church and state. Finally, the great medieval unity of Christianity was shattered by the religious theories that culminated in the Protestant Reformation.