Justification by Faith

I trust I have now sufficiently shown how man's only resource for escaping from the curse of the law, and recovering salvation, lies in faith; and also what the nature of faith is, what the benefits which it confers, and the fruits which it produces. The whole may be thus summed up: Christ given to us by the kindness of God is apprehended and possessed by faith, by means of which we obtain in particular a twofold benefit; first, being reconciled by the righteousness of Christ, God becomes, instead of a judge, an indulgent Father; and, secondly, being sanctified by his Spirit, we aspire to integrity and purity of life....

A man is said to be justified in the sight of God when in the judgment of God he is deemed righteous, and is accepted on account of his righteousness; for as iniquity is abominable to God, so neither can the sinner find grace in his sight, so far as he is and so long as he is regarded as a sinner. Hence, wherever sin is, there also are the wrath and vengeance of God. He, on the other hand, is justified who is regarded not as a sinner, but as righteous, and as such stands acquitted at the judgment-seat of God, where all sinners are condemned. As an innocent man, when charged before an impartial judge, who decides according to his innocence, is said to be justified by the judge, as a man is said to be justified by God when, removed from the catalogue of sinners, he has God as the witness and assertor of his righteousness....

For unless you understand first of all what your position is before God, and what the judgment which he passes upon you, you have no foundation on which your salvation can be laid....

On the contrary, a man will be justified by faith when, excluded from the righteousness of works, he by faith lays hold of the righteousness of Christ, and clothed in it appears in the sight of God not as a sinner, but as righteous. 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....

...[W]hen Christ upbraids the Pharisees for justifying themselves, (Luke 16: 15,) he means not that they acquired righteousness by acting properly, but that they ambitiously courted a reputation for righteousness of which they were destitute....

"Who shall lay any thing to the charge of God's elect? It is God that justifieth. Who is he that condemneth? It is Christ that died, yea rather, that is risen again, who is even at the right hand of God, who also maketh intercession for us, (Rom. 8: 33, 34.) For it is just as if he had said, Who shall accuse those whom God has acquitted? Who shall condemn those for whom Christ pleads? To justify therefore, is nothing else than to acquit from the charge of guilt, as if innocence were proved.... 

Hence, when God justifies us through the intercession of Christ, he does not acquit us on a proof of our own innocence, but by an imputation of righteousness, so that though not righteous in ourselves, we are deemed righteous in Christ. Thus it is said, in Paul's discourse in the Acts, "Through this man is preached unto you the forgiveness of sins; and by him all that believe are justified from all things from which ye could not be justified by the law of Moses," (Acts 13: 38, 39.)...

Thus when the publican is said to have gone down to his house "justified," (Luke 18: 14,) it cannot be held that he obtained this justification by any merit of works. All that is said is, that after obtaining the pardon of sins he was regarded in the sight of God as righteous. He was justified, therefore, not by any approval of works, but by gratuitous acquittal on the part of God.... 

Paul... designates justification by the term acceptance, ... wherein he has made us accepted in the Beloved," (Eph. 1: 5, 6.)  Even as David also describes the blessedness of the man to whom God imputes righteousness without works, saying, "Blessed are they whose iniquities are forgiven," &c., (Rom. 4: 6-8.) ....He pronounced him blessed who has obtained the free pardon of his sins....

But the most satisfactory passage on this subject is that in which he declares the sum of the Gospel message to be reconciliation to God, who is pleased, through Christ, to receive us into favor by not imputing our sins, (2 Cor. 5: 18-21.)....

[S]ince a great part of mankind imagine a righteousness compounded of faith and works let us here show that there is so wide a difference between justification by faith and by works, that the establishment of the one necessarily overthrows the other.

‎...You here see a comparison of contraries, and an intimation that every one who would obtain the righteousness of Christ must renounce his own. Hence he elsewhere declares the cause of the rejection of the Jews to have been, that "they being ignorant of God's righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God," (Rom. 10: 3.).... 

Now if faith utterly excludes boasting, the righteousness of works cannot in any way be associated with the righteousness of faith. This meaning is so clearly expressed in the fourth chapter to the Romans as to leave no room for cavil or evasion. "If Abraham were justified by works he has whereof to glory;" and then it is added, "but not before God," (Rom. 4: 2.) The conclusion, therefore, is, that he was not justified by works....

Scripture, when it treats of justification by faith, leads us in a very different direction. Turning away our view from our own works, it bids us look only to the mercy of God and the perfection of Christ. The order of justification which it sets before us is this: first, God of his mere gratuitous goodness is pleased to embrace the sinner, in whom he sees nothing that can move him to mercy but wretchedness, because he sees him altogether naked and destitute of good works....

[N]o man is justified by the law in the sight of God, it is evident: for, The just shall live by faith. And the law is not of faith: but, The man that does them shall live in them," (Gal. 3: 11, 12; Hab. 2: 4.)

Source: John Calvin, Institutes of the Christian Religion.