Such faith and trust in the mercy of God are extolled, particularly in the Prophets and Psalms, as the highest and the most holy worship of God. For although the law does not, like the Gospel, chiefly preach grace and the remission of sin, yet the promises respecting the coming Christ were handed down from one Patriarch to the other, and they knew and believed, that God would give blessings, grace, comfort, and salvation, through Christ, the blessed seed. Hence, if they understood that Christ was to be the treasure, paying for our sins, they knew that our works could never pay off so great a debt. They therefore received grace, salvation, and remission of sin, without any merit, and were saved through faith in the divine promises and the Gospel of Christ, as well as we, or the saints in the New Testament.

Hence the frequent repetition of the words mercy, goodness, faith, in the Psalms and Prophets; as, in Psalms 130:3–6; “If thou, LORD, shouldst mark iniquities, O LORD, who shall stand?” Here David confesses his sins, and boasts of no merit; but continues:“But there is forgiveness with thee, that thou mayest be feared.” Now he is comforted again, relies on grace and mercy, trusts in the divine promises, and says: “My soul waiteth for the Lord, and in his word do I hope.” And again:“My soul waiteth on the Lord;” that is, as thou hast promised forgiveness of sin, I will hold to thy word; I will trust and rely upon thy gracious promises.   (Henkel Translation, p. 167-168).

Therefore, when we speak of justifying faith, (fide justificante,) it includes first, the divine promises; secondly, that they offer grace freely and without our merit; thirdly, that the blood of Christ and his merits are the treasure which atones for our sins. The promises are received through faith; but as they offer grace without merit, all our worthiness and merit fall to the ground, and grace and boundless mercy alone are praised. The merit of Christ is the treasure; for that must indeed be a treasure and a noble pledge, which pays for the sins of the whole world. All the Scriptures, of the Old and New Testaments, when speaking of God and faith, often use the expressions—goodness, mercy; and in all their writings the holy Fathers teach, that we are saved by grace, goodness, and forgiveness.

Now whenever we find the word mercy in the Scriptures, or in the writings of the Fathers, we must remember, that it refers to faith, which embraces the promise of such mercy.

Again, whenever the Scriptures speak of faith, they mean the faith which is based upon grace alone. For faith does not justify us before God, as though it were in itself our work, and our own, but solely because it receives the grace; promised and offered without merit and presented out of the rich treasures of mercy. (Henkel Translation, p. 167).

From this it is easy to perceive the difference between faith, and the piety produced by the law. For faith is a divine worship and service, (latria,) in which we are the recipients of gifts; but the righteousness of the law is a worship which offers our works to God. Accordingly, God requires us to worship him through faith, that we may receive from him what he promises and offers. Faith, however, is not a mere historical knowledge, but a conviction which firmly cleaves to the divine promises, as Paul fully shows, when he says, Rom. 4:16: “Therefore it is of faith, that it might be by grace; to the end of the promise might be sure to all the seed.” Here Paul so connects the two, that faith, &c., must follow promises; and again, reciprocally, where promises are given, God also requires faith.

But we can show even more plainly, what justifying faith is, by referring to our own Creed and Faith; for the Symbol says: I believe in the remission of sin. Hence it is not enough for us to know or believe that Christ was born, that he suffered and rose from the dead, but we must also believe the article which sets forth the final object of all this, namely, “I believe that my sins are forgiven me.” To this article all the rest must be referred, namely, that our sins are forgiven for Christ’s sake, and not on account of our merit. For why should God give Christ for our sins, if our merit could atone for them?  (Henkel Translation, p. 166-167).