At the age of eighteen in 1501 he entered the University of Erfurt. In 1507 he was ordained to the priesthood. In 1508 he began teaching philosophy at the University of [[Wittenberg]. He continued his theological studies.
In 1517 he posted a document known as the 95 Theses on the door of the church in Wittenburg, Germany. In the 95 Theses, he objected to many policies and doctrines of the Roman Catholic Church. Luther's action was in great part a response to the selling of indulgences by Johann Tetzel, a Dominican priest. Luther's charges directly challenged the position of the clergy as regards to individual salvation. From the viewpoint of the Church, Luther's views were at least schismatic, and possibly heretical. Consequently Luther was called to defend his theses at the Diet of Worms in 1521.
This event is usually taken to mark the beginning of the Protestant movement, which split from the Catholic church in the largest division of western Christianity. However, it is clear that Luther began his work inside the church and only later - and with some reluctance - realized that he was leading a movement away from communion with Rome.
The translation of the Old Testament followed in 1534. He chose to omit parts of the Old Testament that were found in the Greek Septuagint but not in the Hebrew Masoretic texts then available. Those parts were eventually omitted by nearly all Protestants, and are known in Protestant circles as the Apocrypha.
See also: Erasmus of Rotterdam