The Roman Catholic Church dominated many aspects of medieval European society, including education, morality, literacy, and communication. In the 15th century, some individuals like Jan Huss and John Wycliffe began challenging the authority and corruption of the Catholic Church. Martin Luther also had doubts about practices like indulgences and the authority of the Pope. He posted his 95 Theses in 1517, criticizing indulgences and corruption in the Catholic Church, which helped spark the Protestant Reformation.