The Protestant Reformation in Europe was initiated by Martin Luther's actions in 1517, particularly his posting of the Ninety-Five Theses on the door of the Wittenberg Castle Church. In these theses, Luther criticized the Catholic Church's sale of indulgences and called for reforms. His arguments emphasized the importance of scripture, individual faith, and direct access to God, challenging the Catholic Church's authority. This movement sparked religious, cultural, and political upheaval across Europe, leading to the emergence of various Protestant denominations and significant changes in the Christian landscape.