Church officials are corrupt! Stop making us pay taxes, especially outside Rome! Stop selling indulgences! Stop using our money for personal pleasure!
The Great Schism occurred in 1378. A major cause of this was Pope Clement V's decision to move the Catholic government from Rome to Avignon. After this, most of the popes were French, leading the Europeans and other Church officials to think that the French king was controlling the pope. In 1414, the emperor of the Holy Roman Empire summoned a conference to end the schism. The French pope was removed and the Roman pope resigned. After Pope Martin V was elected, he helped to reunify the Church.
Many reformers were angry with the Church and how they earned and spent their money. Many Europeans were angry since they had to pay taxes to the Church in Rome even if they lived outside of Italy, but the Church payed no tax on their land. Others were mad about the selling of indulgences, and they were enraged that the Church was selling people into heaven. More people were mad about the way the Church spent their money. They used the money they got through the Church for art and their own pleasures. All this led to Martin Luther starting the Reformation.