The most suitable option is they believed that the Church had moved away from its core teachings and became corrupt.
Between 1400 and 1500 occured significants changes in the Roman Catholic Church. During this period, people criticized that Cardinals and Popes were concentrated in worldly issues instead of caring for faith. They lived more than kings living in luxury while peope starved to death and many of their practices did not match with what the Bible said. These are the reasons why people wanted to reform the Catholic Church.
