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. The Church took offense to his questions and branded him as a traitor to the church.
He defended the theses in Worms.
This marked the beginning of the Protestant movement, which split from the Catholic church in the largest division of western Christianity.
Luther translated the New Testament into German. It was published in 1521. The translation of the Old Testament followed in 1534.
Today most Protestant denominations follow ideas based in Luther's teachings, and the Lutheran Church in particular is directly descended from his work.