Forgiveness of Sins and Righteousness...

Gospel truths that the most saintly Christian never outgrows:

"The sum of the Gospel is, not without good reason, made to consist in repentance and forgiveness of sins; and, therefore, where these two heads are omitted, any discussion concerning faith will be meager and defective, and indeed almost useless. 

"... nothing belongs more peculiarly to God than the forgiveness of sins, in which our salvation consists. 

"... Thus we simply interpret justification, as the acceptance with which God receives us into his favor as if we were righteous; and we say that this justification consists in the forgiveness of sins and the imputation of the righteousness of Christ. 

".... in the Epistle to the Romans, he proves, by the testimony of David, that righteousness is imputed without works, because he declares the man to be blessed "whose transgression is forgiven, whose sin is covered," and "unto whom the Lord imputeth not iniquity," (Romans 4:6; Psalm 32:1, 2.) There he undoubtedly uses blessedness for righteousness; and as he declares that it consists in forgiveness of sins, there is no reason why we should define it otherwise... 

"Thus the Apostle connects forgiveness of sins with justification in such a way as to show that they are altogether the same; and hence he properly argues that justification, which we owe to the indulgence of God, is gratuitous. Nor should it seem an unusual mode of expression to say that believers are justified before God not by works, but by gratuitous acceptance, seeing it is frequently used in Scripture, and sometimes also by ancient writers. Thus Augustine says: "The righteousness of the saints in this world consists more in the forgiveness of sins than the perfection of virtue," (August. de Civitate Dei, lib. 19, cap. 27.) To this corresponds the well-known sentiment of Bernard: "Not to sin is the righteousness of God, but the righteousness of man is the indulgence of God," (Bernard, Serm. 22, 23 in Cant.) He previously asserts that Christ is our righteousness in absolution, and, therefore, that those only are just who have obtained pardon through mercy."

John Calvin, Institutes 3.11