Luther, Martin (1483–1546), German Reformation leader and founder of Lutheranism. Following a religious experience he became an Augustinian friar, was ordained in 1507, and visited Rome (1510), where he was shocked by the worldliness of the papal court. While professor of Scripture at the Univ. of Wittenberg (from 1512), he wrestled with the problem of personal salvation, concluding that it comes from the unmerited grace of God, available through faith alone. When Johann Tetzel toured Saxony (1517) selling papal indulgences, Luther denounced the practice in his historic 95 theses, for which he was fiercely attacked. In 1520 he published To the Christian Nobility of the German Nation. It denied the pope's final authority to determine the interpretation of Scripture, declaring instead the priesthood of all believers, and it rejected papal claims to political authority, arguing for national churches governed by secular rulers. Luther denied the special spiritual authority of priests and advocated clerical marriage. In Dec. 1520 he publicly burned a papal bull of condemnation and a copy of the canon law; he was excommunicated in 1521. Summoned by Emperor Charles V to renounce his heresies at the Diet of Worms (1521), he refused. He was outlawed but, protected by Frederick III of Saxony, he retired to the Wartburg castle. There he translated the New Testament into German in 6 months and began work on the Old. His hymns have been translated into many languages, and he wrote 2 catechisms (1529), the basis of Lutheranism.