The words “imputation” and “justification” are seldom used in the church today, but they are essential for understanding the Christian doctrine of salvation. Before explaining why the imputation of Christ’s righteousness is essential for justification, we need to define what justification and imputation are. Justification is the legal declaration by God that our sins are forgiven and will never be taken into account because Jesus has paid the penalty for those sins and his sinless righteousness is credited to us so that we stand in the presence of God with his righteousness and not our own. Justification involves both the non-imputation of sin in forgiveness and the imputation of Christ’s righteousness which is the basis upon which we are justified or declared righteous by God.
Imputation is the reckoning or crediting to our account the righteousness, obedience, and sinlessness of Christ to us. Christ’s righteousness is considered in two aspects: his active obedience in his perfect life of obedience to the Father and his passive obedience enduring the punishment of the law. His life is now our life and his death is our death. We were condemned with him on the cross and vindicated with him in his resurrection because we were in union with him from God’s perspective. Our sins which did not yet exist were imputed to him on the cross and his righteous obedience to God is imputed to us in justification. Christ took our sins and we receive his righteousness. This is the great exchange.
The imputation of Christ’s righteousness is essential for justification because otherwise God would be unjust to declare us to be righteous when we are not righteous in his sight. We need the righteousness of another, the righteousness of God. Just as Christ’s death is necessary for our salvation to satisfy God’s justice and wrath for our sins, Christ’s sinless life is necessary for God to have a basis upon which to declare us to be something we are not actually in ourselves. God “justifies the ungodly” (Rom 4:5) when it is an abomination for a judge to justify the wicked (Prov 17:15). God can only do this because of the propitiatory work of Christ which allows him to remain just when he justifies us (Rom 3:25-26).
Our problem as sinners is twofold: we have broken God’s law and are therefore deserving of punishment and we have no righteousness of our own to bring before God. We need forgiveness and we need righteousness because we have never kept God’s law as it deserves to be kept. The propitiatory death of Christ covers over our sins with his blood so that God does not take them into account and his righteous life becomes ours in justification so that God sees us through the lens of his Son. When God looks upon his children in justification, he sees no sin upon them because Christ bore those sins away on the cross (Col 2:13-14). And he sees them standing in the garments of Christ’s righteousness so that he cannot but accept them into his presence. The Father will never reject his Son and he will never reject those who come to him through his Son. The Father will never turn away those who are in union with Christ since they are part of his bride.
A key text for understanding imputation is 2 Corinthians 5:21: “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.” How do we become “the righteousness of God” in Christ? – The same way Christ became sin on the cross. Jesus never sinned in thought, word, or deed. He is the spotless Lamb of God who became sin through the imputation of our sins to him on Calvary (1 Pet 2:22-24). Our sins were laid on him and he bore them away never to be seen again (Lev 16:21-22; Isa 53:5-6). He never became a sinner with regard to himself, but legally and imputationally with regard to the sins of others in having their sins credited to him on the cross to satisfy God’s justice for them.
Likewise, we become the righteousness of God legally and imputationally in justification by having his righteousness credited to us. We do not actually become sinless in ourselves the moment we are justified just as Christ did not actually become sinful on the cross. Christ was treated as the greatest sinner of all time for our sins and we are treated the way Christ deserves to be treated. Christ was condemned for our sins and we are declared righteous on the basis of his righteousness. Christ bore our sins and we bear his righteousness. The sinless one was condemned even though he never sinned so that sinners might be declared righteous even though they have no righteousness of their own. For more on the doctrine of imputation, see Jesus’ Blood and Righteousness by Brian Vickers.