Only by true faith in Jesus Christ; that is, although my conscience accuse me, that I have grievously sinned against all the commandments of God, and have never kept any of them, and am still prone always to all evil; yet God without any merit of mine, of mere grace, grants and imputes to me the perfect satisfaction, righteousness, and holiness of Christ, as if I had never committed nor had any sin, and had myself accomplished all the obedience which Christ has fulfilled for me; if only I accept such benefit with a believing heart.

— Heidelberg Catechism 60

In part 4 we considered what Scripture teaches and thus what we confess about the ground of our justification: the imputation of Christ’s righteousness. It is proper to him, it belongs by nature to him. He earned it. He condignly merited it. He deserved it. He was inherently, intrinsically righteous. By nature, all that Christ is and did is alien to us. This is why the Protestants in the 16th century spoke of Christ’s “alien righteousness” (iustitia aliena).  Nevertheless, only by God’s free grace, by his favor, all that Christ did, all of his righteousness, all of his condign merit, all of his perfect, whole, active and suffering (passive) obedience is credited or imputed or reckoned to us. Thus, when God looks at us, with respect to justification, he does not see our sin. He sees only Christ’s perfect righteousness. Sometimes it is said that justification means that it is as if I had never sinned but that is only half the story. Not only are all our sins forgiven but we are made positively righteous before God. It is as if we ourselves had done all that Christ has done for us.

How do we lay hold of Christ’s righteousness? How does it become ours? How do we come into possession of that righteousness by which we can stand before God not only forgiven but actively righteous as perfect law keepers?

…yet we know that a person is not justified by works of the law but through faith in Jesus Christ, so we also have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified (Gal 2:16; ESV)

Now it is evident that no one is justified before God by the law, for “The righteous shall live by faith.” 12 But the law is not of faith, rather “The one who does them shall live by them.” (Gal 3:11–12; ESV)

For in it the righteousness of God is revealed from faith for faith,as it is written, “The righteous shall live by faith.” (Rom 1:17; ESV)

But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— 22 the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: 23 for all have sinned and fall short of the glory of God, 24 and are justified by his grace as a gift, through the redemption that is in Christ Jesus, 25 whom God put forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins. 26 It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus. Then what becomes of our boasting? It is excluded. By what kind of law? By a law of works? No, but by the law of faith. 28 For we hold that one is justified by faith apart from works of the law. (Rom 3:21–27; ESV)

And to the one who does not work but believes in him who justifies the ungodly, his faith is counted as righteousness (Rom 4:5; ESV)

That is why it depends on faith, in order that the promise may rest on grace and be guaranteed to all his offspring—not only to the adherent of the law but also to the one who shares the faith of Abraham, who is the father of us all….(Rom 4:16; ESV)

Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ. (Rom 5;1; ESV)

Did you notice a theme emerging in these verses? In every case what was the instrument by which we are said to lay hold of Christ’s righteousness or by which we are justified? Faith. That’s the significance of the Latin phrase sola fide. It’s an instrumental phrase. That’s why we should not speak of “faith alone” (sola fides) “by faith alone” or “through faith alone.” Faith is the sole instrument of our justification. It’s the sole means by which we lay hold of what Christ has done. Paul repeatedly and explicitly excluded anything done by us (works) or even anything wrought in us by God’s grace (sanctification). Rome agrees that we are justified by grace and faith but she omits the “alone.” This is why Luther added “allein” (alone) to his German translation of Galatians 3:28. This is why Calvin insisted that when we’re discussing our justification that we do not mention works at all and that we adhere resolutely to the “exclusive particle.” By grace alone God grants and imputes to us Christ’s righteousness. There is nothing in us, not even that which is worked by grace, that is a cause for his grace. The cause is in himself. Faith is the unique and only instrument by which we apprehend Christ and his righteousness, the only instrument through which we receive what Christ has done for us (pro nobis).

Look at those passages closely in their context. In none of them is faith considered to be, in itself, a powerful, Spirit-wrought virtue that sanctifies us unto justification. Rome sees and teaches that because she knows before she ever gets to Scripture that God can only say what he does (“justified”) if, in fact, inherently, we are already righteous by grace and cooperation with grace. This is why she re-defines “works” to mean obedience to the ceremonial laws. Does that sound familiar? It should. That’s also the view of many ostensibly “evangelical” and even some ostensibly “Reformed” folk. That’s not what the evangelical and Reformed faith confesses however. Scripture teaches repeatedly, clearly, unequivocally that all our works, all our doing, all our obedience is excluded from the ground and the instrument of our justification. That is why we confess in Belgic Confession art. 24 that we are justified “even before we do good works.”

That is why we confess, “if only I accept such benefit with a believing heart.” We cannot earn God’s favor. Stop trying. Christ has earned God’s favor for all his people. Confess your sins and sinfulness and put your trust in Christ and his finished work. That’s why Jesus said, “It is finished,” because it is. Every time you try to earn favor with God and refuse to put your trust solely in Christ and in his finished work you insult him by suggesting that Christ’s work for us is not sufficient. It is. How are sinners justified before God? Only by true faith. Our conscience may say what it will. The law of God convicts us. Satan may whisper that we have not done enough but we have a short reply: it is finished. To that we may only add “It is mine by faith alone. Go away.”

Here are all the posts on the Heidelberg Catechism.