Jean Calvin was a French theologian and reformer who played a significant role in the Protestant Reformation during the 16th century. He is best known for his teachings on predestination and the sovereignty of God, which became central tenets of Calvinism. His influential work, "Institutes of the Christian Religion," laid the foundation for Reformed theology and emphasized the importance of scripture. Calvin settled in Geneva, where he established a theocratic government and implemented strict moral codes. His leadership helped shape the city into a center of Protestant thought and practice. Today, Calvin's ideas continue to influence various Christian denominations, particularly those within the Reformed tradition.