Next time you are plagued by feelings of guilt, fear of God’s anger, or a sense that you don’t measure up to his standards, recall that Christ has already met those standards on your behalf—“irrevocably, immutably and indefectibly” (Fesko, p. 278). And remember this verse, whose truths flow from this perfect imputation of Christ’s perfect life: “He will rejoice over you with gladness; he will quiet you by his love; he will exult over you with loud singing.” (Zeph. 3:17) The salvation Christ has won for you cannot be taken away. Be at peace, and take joy in your Savior.
Do you struggle with guilt? Do you sometimes wonder how God could possibly love such a wretched sinner as you? Do you ever get depressed because you feel as though you don’t “measure up”?
Many Christians wrestle with these feelings, even though they started their spiritual journey by acknowledging that all their sins are forgiven through Jesus’ sacrificial death. We learn this key truth from such passages as 1 Peter 2:24 (“He himself bore our sins in his body on the tree”) and from Isaiah 53:
But he was pierced for our transgressions;
he was crushed for our iniquities;
upon him was the chastisement that brought us peace,
and with his wounds we are healed. (Isa. 53:5)
While these verses explain how can we be reconciled to God even though we are sinners who fail to keep his law, how does God remove the burden of depressing guilt over our sin?
Believers are declared righteous in Christ.
The answer is that rather than making us holy and sinless persons, God declares us righteous based not on our works but instead on what Christ did for us. In other words, it is not our works that remove our guilt and save us. Instead, it is what Christ did—that is, the work he did for us in both his life and death. Our receiving and benefiting from the work of Jesus for our salvation is often referred to by the term “imputation,” a word that describes the act of assigning or attributing something to someone else.
Understanding the word imputation is essential to resting in Christ.
We find three areas of imputation in the Bible, and understanding each of them helps us not to worry about whether we have enough righteousness for God to be pleased with us or whether we are truly saved.
Imputation #1: Adam’s first sin is imputed (credited or counted) to all his posterity—as described at length in Romans 5: We “all sinned” when Adam did, and thus, “by the one man’s disobedience the many were made sinners” (vv. 12-19). The theologian John Murray is helpful here, explaining how the Greek word for “made” (kathestemi) is better translated as “constituted,” meaning that we “were placed in the category of sinners.” 
Imputation #2: In this case, our sins are imputed to Christ, and he suffers the penalty due for sin in our place. Thus, the apostle Paul writes in 2 Corinthians 5:21: “For our sake he made him to be sin who knew no sin,” fulfilling Isaiah’s earlier words: “The Lord has laid on him the iniquity of us all” (Isa. 53:6). Since Christ has been “offered once to bear the sins of many” (Heb. 9:28), we no longer need to fear God’s wrath for our failures and transgressions.
Imputation #3: Jesus’ perfect obedience and righteousness are imputed to all believers in Christ, so that we stand before the Father, not merely forgiven for our sins, but also bearing the spotless perfection of Christ’s lifelong obedience—as though we ourselves had also lived that flawless and exemplary life (Rom. 5:17-19; 3:21-24; 10:5-13).
This crucial third imputation listed above regarding Christ’s righteousness is stressed in several passages of Scripture. In Romans 5:19, right after indicating that we were “made sinners” in Adam, Paul concludes that in the same way, “many will be made righteous” (now placed in the category of the righteous) by “the one man’s obedience.” Similarly, Isaiah 53:11 declares, “By his knowledge shall the righteous one, my servant, make many to be accounted righteous.” And 2 Corinthians 5:21 links the two imputations in one glorious verse: “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.”
Imputation is an important core doctrine of the historical church.
The Westminster Confession of Faith, a summary of Christian doctrine written in the seventeenth-century, stressed the importance of the doctrine of imputation in its chapter on justification.