The Reformation, initiated in the early 16th century, significantly altered the European religious landscape by challenging the Catholic Church's authority. Figures like Martin Luther and John Calvin advocated for reforms, leading to the rise of Protestant denominations such as Lutheranism and Calvinism. This religious upheaval prompted conflicts, including the Thirty Years' War, and eventually led to the establishment of various religious freedoms in Europe. The Reformation's impact extended beyond religion, influencing politics, education, and individualism, while laying the groundwork for the secularization of society and the rise of Enlightenment thought.