Martin Luther OSA (/ˈluːθər/; German: [ˈmaʁtiːn ˈlʊtɐ] (listen); 10 November 1483 – 18 February 1546) was a German priest, theologian, author and hymnwriter. A former Augustinian friar, he is best known as the seminal figure in the Protestant Reformation and as the namesake of Lutheranism. Luther was ordained to the priesthood in 1507. He came to reject several teachings and practices of the Roman Catholic Church; in particular, he disputed the view on indulgences. Luther proposed an academic discussion of the practice and efficacy of indulgences in his Ninety-five Theses of 1517. His refusal to renounce all of his writings at the demand of Pope Leo X in 1520 and the Holy Roman Emperor Charles V at the Diet of Worms in 1521 resulted in his excommunication by the pope and condemnation as an outlaw by the Holy Roman Emperor.