Martin Luther was educated by those late-medieval theologians who taught that God would not refuse to give grace to those who “did what was in them.” Luther taught this view in his earliest lectures. Gradually, however, he began to understand how seriously flawed that view was and began to reject the Pelagian tendencies in his thinking and move toward a more Augustinian view. Sometime between 1517 and 1520, Luther moved even further when he finally came to understand the distinction between justification and sanctification. He was helped along in this by Philip Melanchthon, whose expertise in the Greek language helped Luther come to a more biblically faithful definition not only of justification but of grace and faith as well.
In these years between 1517 and 1520, as Luther began to raise objections to the practices of the church, his Roman Catholic opponents focused first and foremost on the question of authority. Luther was forced to dig deeper on this subject, and as he realized that various popes had contradicted themselves many times, he began to emphasize the idea that Scripture alone is our one infallible and divinely authoritative source for doctrine. Rome pushed back. Ultimately, Luther’s views led to his excommunication by the church and the call for him to appear before the emperor at the Diet of Worms.
Luther’s doctrine of Scripture and his doctrine of justification are arguably his two most important theological legacies. In both cases, he stepped into long-standing theological disputes and took a stand. In both cases, his stand forced Rome to respond, and in both cases, Rome chose views that had the least support in both Scripture and the historical church.
Luther’s legacy as regards his doctrine of justification finds its initial ecclesiastical expression in the Augsburg Confession of 1530 and the documents that resulted from it. The Augsburg Confession was written by Philip Melanchthon, but Luther heartily approved of it. The article on justification reads:
Also they [the Lutherans] teach that men cannot be justified before God by their own strength, merits, or works, but are freely justified for Christ’s sake, through faith, when they believe that they are received into favor, and that their sins are forgiven for Christ’s sake, who, by His death, has made satisfaction for our sins. This faith God imputes for righteousness in His sight. Rom. 3 and 4.
Regarding sanctification, the confession reads:
Also they teach that this faith is bound to bring forth good fruits, and that it is necessary to do good works commanded by God, because of God’s will, but that we should not rely on those works to merit justification before God. For remission of sins and justification is apprehended by faith, as also the voice of Christ attests: When ye shall have done all these things, say: We are unprofitable servants. Luke 17:10. The same is also taught by the Fathers. For Ambrose says: It is ordained of God that he who believes in Christ is saved, freely receiving remission of sins, without works, by faith alone.
The Augsburg Confession eventually became one of the confessional standards of the Lutheran church when it was included in the Book of Concord in 1580.