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).