IMPUTATION
A forensic term that denotes the reckoning or placing to a person’s account the merit or guilt that belongs to him on the basis of his personal performance or of that of his federal head. While impute is used in Scripture to express the idea of receiving the just reward of our deeds (Lev. 7:18; 17:4; 2 Sam. 19:19), imputation as a theological term normally carries one of two meanings:
Imputation of Adam’s Sin
First, it describes the transmission of the guilt of Adam’s first sin to his descendants. It is imputed, or reckoned, to them; i.e., it is laid to their account. Paul’s statement is unambiguous: “By one man’s disobedience many were made [constituted] sinners” (Rom. 5:19). Some Reformed theologians ground the imputation of Adam’s sin in the real involvement of all his posterity in his sin, because of the specific unity of the race in him. Shedd strongly advocates this view in his Dogmatic Theology. Others—e.g., Charles and A. A. Hodge, and Louis Berkhof—refer all to the federal headship of Adam. The Westminster Standards emphasize that Adam is both the federal head and the root of all his posterity. Both parties accept that this is so. Thus, the dispute is not whether Adam’s federal headship is the ground of the imputation of his first sin to us, but whether that federal headship rests solely on a divine constitution—i.e., because God appointed it—or on the fact that God made him the actual root of the race and gave the race a real specific unity in him.
The theory of mediate imputation has never gained acceptance in orthodox expressions of the Reformed Faith. It is subversive to the entire concept of the imputation of Adam’s sin upon which Paul grounds his exposition of justification by virtue of union with Christ our righteousness (Rom. 5:12–19; 1 Cor. 15:22).
Paul’s statement of the imputation of Adam’s sin to his posterity is stark: “By [through] one man sin entered into the world, and death by [through] sin; so death passed upon all men, for all have sinned” (Rom. 5:12). In the AV the clause “for all have sinned” may give the impression that Paul’s argument is that all die like Adam because all, like him, have sinned. But this is not the case. His statement is, “Death passed upon all humanity inasmuch as all sinned.” He teaches that all participated in Adam’s sin and that both the guilt and the penalty of that sin were transmitted to them. However we explain the mode of that participation—whether on purely federal or on traducianist-federal grounds—the fact of it stands as a fundamental of the Christian revelation. As the Shorter Catechism says, “The covenant [of works] being made with Adam, not only for himself, but for his posterity, all mankind, descending from him by ordinary generation, sinned in him, and fell with him, in his first transgression” (Question 16, emphasis added.)
Imputation of our Sin to Christ and of His Righteousness to Us
Second, imputation has a second major use in Scripture. It describes the act of God in visiting the guilt of believers on Christ and of conferring the righteousness of Christ upon believers. In this sense
“imputation is an act of God as sovereign judge, at once judicial and sovereign, whereby He—(1). Makes the guilt, legal responsibility of our sins, really Christ’s, and punishes them in Him, Isa. 53:6; John 1:29; 2 Cor. 5:21; and (2). Makes the merit, legal rights of Christ’s righteousness, ours, and then treats us as persons legally invested with all those rights, Rom. 4:6; 10:4; 1 Cor. 1:30; 2 Cor. 5:21; Phil. 3:9. As Christ is not made a sinner by the imputation to Him of our sins, so we are not made holy by the imputation to us of His righteousness. The transfer is only of guilt from us to Him, and of merit from Him to us. He justly suffered the punishment due to our sins, and we justly receive the rewards due to His righteousness, 1 John 1:8, 9”
(A. A. Hodge, Outlines of Theology, chap. 30, Q. 15).
The fact of this imputation is inescapable: “By the obedience of one [Christ] shall many be made righteous” (Rom. 5:19). The ground of it is the real, vital, personal, spiritual and federal union of Christ with His people. It is indispensable to the biblical doctrine of justification. Without it, we fail to do justice to Paul’s teaching, and we cannot lead believers into the comfort that the gospel holds out to them. That comfort is of a perfect legal release from guilt and of a perfect legal righteousness that establishes a secure standing before God and His law on the basis of a perfect obedience outside of their own subjective experience.
The double imputation of our sin to Christ and of His righteousness to us is clearly laid down in 2 Cor. 5:21: “He hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.” Hugh Martin’s paraphrase catches the meaning precisely: “God made him, who knew no sin, to be sin for us, who knew no righteousness, that we might be made the righteousness of God in him.” That Paul means us to understand a judicial act of imputation is clear. God did not make Christ personally a sinner. The reference is not to Christ’s subjective experience. He was as personally sinless and impeccable when He was bearing our sins on the cross as He had ever been. What Paul is describing is God’s act of reckoning our sin to Christ so as to make Him legally liable for it and all its consequences. Similarly, while believers are not by any means righteous in their subjective experience, God reckons to them the full merit of Christ’s obedience in life and death (Rom. 5:18, 19). That righteousness, not any attained virtue, is the ground of a believer’s acceptance with God.
Source: Cairns, A. (2002). Dictionary of Theological Terms (pp. 225–226). Belfast; Greenville, SC: Ambassador Emerald International.