On October 31, 1517. Martin Luther, a 33-year-old theology professor at Wittenberg University walked over to the Castle Church in Wittenberg and nailed a paper of 95 theses to the door, hoping to spark an academic discussion about their contents. It became a key event in igniting the Reformation.
John Calvin (1509–1564) was an influential French theologian and pastor during the Protestant Reformation. He was a principal figure in the development of the system of Christian theology later called Calvinism. John Calvin was Martin Luther's successor as the preeminent Protestant theologian. Calvin made a powerful impact on the fundamental doctrines of Protestantism, and is widely credited as the most important figure in the second generation of the Protestant Reformation.