Martin Luther was a German priest, theologian, author, hymnwriter, professor, and former Augustinian friar. Luther was the seminal figure of the Protestant Reformation, and his theological beliefs form the basis of Lutheranism. He is widely regarded as one of the most influential figures in Western and Christian history.
Born in Eisleben, Luther was ordained to the priesthood in 1507. He came to reject various teachings and practices of the Roman Catholic Church, in particular the view on indulgences and papal authority. Luther initiated an international debate on these in works like his Ninety-five Theses, which he authored in 1517. In 1520 Pope Leo X demanded that Luther renounce all of his writings, and when Luther refused to do so, excommunicated him in January 1521.