Without quite intending to, Martin Luther changed the course of Christianity and Western history. His 1517 complaint against specific abuses in the Roman Catholic church -- a document now known as the 95 Theses -- sparked the explosive Protestant Reformation that swept Europe for the rest of the century. Born to a Roman Catholic family (his father was a copper miner), Luther graduated from the University of Erfurt in 1505 but abandoned his legal studies to enter a monastery devoted to St. Augustine
. He was ordained to the priesthood in 1507 and by 1512 was a doctor of theology and a Bible professor at the University of Wittenberg. Luther was a gifted preacher but his theology began to clash with that of the Catholic church: he wrote that salvation came not by any human work but by absolute faith in God's promise of forgiveness on account of Jesus Christ
. Luther didn't anticipate the uproar touched off by the 95 Theses he sent to a bishop and archbishop to protest "indulgences" being sold by the Catholic hierarchy under Pope Leo X
. His controversial beliefs earned him excommunication from the church, but he pressed on with many new followers. Luther produced the first reader-friendly German translation of the Bible and developed a new form of Christian worship that emphasized preaching and popular hymns, permitted the clergy to marry, and honored ordinary life in the world as a field for God's service.