The Protestant Reformation began in 1517, marked by Martin Luther's posting of the Ninety-Five Theses on the door of the Wittenberg Castle Church. This event signified a pivotal challenge to the practices of the Catholic Church, particularly indulgences, and called for reforms within Christianity. Luther's actions ignited a widespread movement questioning the authority of the Church and the Pope, eventually leading to the establishment of various Protestant denominations. The Reformation had profound implications for religion, politics, and society in Europe, contributing to significant changes in theological thought and the decline of Catholic hegemony.