The major religious movement in Europe that sought to reform the Catholic Church in the 16th century is known as the Protestant Reformation. Initiated by figures such as Martin Luther and John Calvin, the movement criticized the corruption within the Church, including the sale of indulgences and the church's wealth. Luther's Ninety-Five Theses, which challenged Church practices, sparked widespread debate and led to the establishment of various Protestant denominations. The Reformation had profound implications for Christianity, increasing religious diversity, leading to conflicts such as the Thirty Years' War, and shaping the course of European history towards secularism.