Answer:
The Protestant Reformation was a threat to the power that the Catholic Church had over Europe because the Catholic Church got all of their money from the members of the church. The Church sold indulgences to the people and told the people that if they did not buy indulgences, then they or their loved ones would not go to heaven. Protestants did not believe in the sell of indulgences, so this would cut the Catholic Church's money supply off big time.