“Rom. 4:16 says: ‘Therefore it is of faith that it might be by grace, to the end that the promise might be sure;’ as though he were to say: ‘If the matter were to depend upon our merits, the promise would be uncertain and useless, because we never could determine when we would have sufficient merit.’ And this, experienced consciences can easily understand [and would not, for a thousand worlds have our salvation depend upon ourselves]. Accordingly, Paul says, Gal. 3:22: ‘But the Scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.’ He takes merit away from us, because he says that all are guilty and concluded under sin; then he adds that the promise, namely, of the remission of sins and of justification, is given, and adds how the promise can be received, namely, by faith. And this reasoning, derived from the nature of a promise, is the chief reasoning [a veritable rock] in Paul, and is often repeated… Let not good minds suffer themselves to be forced from the conviction that we receive remission of sins for Christ’s sake, only through faith. In this they have sure and firm consolation against the terrors of sin, and against eternal death, and against all the gates of hell.

“But since we receive remission of sins and the Holy Ghost by faith alone, faith alone justifies, because those reconciled are accounted righteous and children of God, not on account of their own purity, but through mercy for Christ’s sake, provided only they by faith apprehend this mercy. Accordingly, Scripture testifies that by faith we are accounted righteous (Rom. 3:26). We, therefore, will add testimonies which clearly declare that faith is that very righteousness by which we are accounted righteous before God, namely, not because it is a work that is in itself worthy, but because it receives the promise by which God has promised that for Christ’s sake He wishes to be propitious to those believing in Him, or because He knows that Christ of God is ‘made unto us wisdom, and righteousness, and sanctification, and redemption’ (1 Cor. 1:30).”

-Apology of the Augsburg Confession IV (II) 84-86