Martin Luther (November 10, 1483 - February 18, 1546) was a German Augustinian friar and professor of theology who challenged the Catholic doctrine of salvation, the authority of the pope and the practice of indulgences.
The publication of his Ninety-Five Theses (1517) marks the beginning of the Protestant Reformation. Pope Leo X excommunicated Luther after the latter refused to retract his writings. Luther opposed the notion that good deeds were necessary to attain salvation, which is to be received or accepted only as a free gift of God's grace through faith in Jesus Christ. He also affirmed, in opposition to Catholic teaching, that the Bible is the only source of divine revelation, and rejected the idea of a sacramental priesthood conferred through Episcopal anointing, considering instead that all baptized Christians share into the same holy priesthood.
His translation of the Bible into the vernacular German encouraged a wider use of the Sacred Scriptures and made them more accessible to the people. The strong anti-Semitism of his later years made him a controversial figure among many historians and religious scholars.