The Protestant Reformation significantly affected the Catholic Church by challenging its authority and prompting internal reforms. The movement, initiated by figures like Martin Luther and John Calvin, led to a fragmentation of Christianity and the establishment of various Protestant denominations. This era saw the Catholic Church respond with its own Counter-Reformation, seeking to rectify abuses, reaffirm doctrines, and regain influence. The Reformation also initiated a cultural shift, emphasizing individual interpretation of the Bible and promoting literacy, which ultimately diminished the Church's monopoly on spiritual matters.