Definition

Original sin is the sinful condition with which every human being (except Christ) enters the world as a consequence of Adam’s first transgression. It comprises two distinct but inseparable parts. First, imputed guilt: because Adam was the federal head of the human race under the covenant of works, the guilt of his first sin is legally reckoned to all his natural posterity, so that all are accounted guilty and condemned in him. Second, inherited corruption: from Adam’s fallen nature there is conveyed to all his descendants a polluted nature, the loss of original righteousness, and a heart wholly inclined to evil. Original sin is thus both a legal liability (we are guilty in Adam) and a moral pollution (we are corrupt from Adam), and it is the source from which all actual sins proceed.

Why It Matters

Original sin explains the universal and inescapable reality of human sinfulness. Why is every human being, in every culture and age, a sinner — and a sinner from the very beginning of life? The answer is not environment or imitation but a corrupt nature inherited from our first father and a guilt imputed from his first sin. This doctrine grounds the necessity of redemption for all, including infants, and exposes the futility of any salvation by human effort, since we are sinful before we have done anything at all.

The doctrine of imputation is also the linchpin of justification. The same principle by which Adam’s guilt is reckoned to us is the principle by which Christ’s righteousness is reckoned to believers. Paul deliberately parallels the two (Rom. 5:18–19). To deny the imputation of Adam’s sin is to undermine the imputation of Christ’s righteousness, and so to imperil the gospel itself. As we fell by another’s act, so we are saved by Another’s act; the logic of grace mirrors the logic of the fall.

Biblical Foundation

The classic text is Romans 5, where Paul roots the universality of sin and death in Adam’s one transgression:

“Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned.” (Rom. 5:12)

The phrase “because all sinned” is decisive. Paul does not mean that all die because all commit personal sins, for he immediately notes that death reigned even over those “whose sinning was not like the transgression of Adam” (Rom. 5:14) — including infants who never broke an express command. Rather, “all sinned” in Adam, their representative; his sin was their sin. This is confirmed by the parallel:

“Therefore, as one trespass led to condemnation for all men … For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous.” (Rom. 5:18–19)

The whole argument turns on representation: one man’s act reckoned to many. “In Adam all die” (1 Cor. 15:22) states the same truth. As for inherited corruption, David confesses, “Behold, I was brought forth in iniquity, and in sin did my mother conceive me” (Ps. 51:5); Job asks, “Who can bring a clean thing out of an unclean? There is not one” (Job 14:4); and Jesus declares, “That which is born of the flesh is flesh” (John 3:6). Paul sums it up: we are “by nature children of wrath” (Eph. 2:3) — sinful by nature, not merely by act.

Key Components & Distinctions

Imputed Guilt (Peccatum Alienum)

The first element of original sin is the imputation of Adam’s first sin. Imputation is a legal, forensic act: God reckons or charges Adam’s guilt to his posterity, not because they personally committed it, but because Adam acted as their covenant head. This is immediate imputation — Adam’s guilt is charged directly to all in him, prior to and apart from any corruption or actual sin of their own. The Reformed insist on the immediate character against those who teach only mediate imputation (that we are accounted guilty only because we inherit a corrupt nature). Scripture grounds condemnation in the one trespass itself (Rom. 5:16–18), so the guilt is reckoned directly.

Inherited Corruption (Peccatum Inhaerens)

The second element is the corrupt nature conveyed from Adam — what the confessions call our “original corruption.” This includes the privation of original righteousness (the loss of the knowledge, righteousness, and holiness in which man was made) and the positive depravity of the whole nature, a heart “wholly inclined to all evil.” This corruption is propagated by ordinary generation: “that which is born of the flesh is flesh” (John 3:6). It is not located in the body alone or transmitted by mere example, but inheres in the soul and pervades every faculty.

The Relation of Guilt and Corruption

Guilt and corruption are distinct but inseparable. The guilt of Adam’s sin is the legal ground of our condemnation; the corruption of nature is its moral consequence and the fountain of all actual sins. Reformed theology holds that the corruption is itself penal — God’s just judgment upon Adam’s race — so that even our depraved nature is part of the curse imputed in Adam. Thus we are both condemned in Adam and corrupted from Adam, and from this corrupt root spring all our personal transgressions.

The Sinfulness of Concupiscence

Reformed theology, with the Reformers, affirms that concupiscence — the disordered desire and inward inclination to evil — is itself truly sin, not merely the tinder or occasion of sin. Against Rome, which holds that concupiscence in the baptized is not properly sin, Scripture teaches that “the desire of the flesh is against the Spirit” (Gal. 5:17) and that coveting is itself a transgression of the law (Rom. 7:7–8). The inward corruption is sin, even before it issues in act.

Historical Development

Augustine, against Pelagius, established the catholic doctrine of original sin: in Adam all sinned, all inherit guilt and corruption, and the will is in bondage. His reading of Romans 5:12 (through the Latin in quo omnes peccaverunt, “in whom all sinned”) grounded inherited guilt, and his teaching was affirmed at Carthage (418) and Orange (529).

The medieval church retained original sin but softened it: through the donum superadditum, the fall removed a superadded gift but left nature relatively intact, and concupiscence was deemed not properly sin. The Reformers recovered the Augustinian fullness, affirming both imputed guilt and pervasive corruption, and the true sinfulness of concupiscence. Within Reformed theology, debate arose over the mode of imputation. The federal (covenantal) view, dominant in Westminster orthodoxy, grounds imputation in Adam’s representative headship. The realist view (associated with W. G. T. Shedd and the older Augustinian tradition) grounds it in the real, seminal presence of all humanity in Adam. The mediate view (Josué de la Place) was condemned by Reformed synods as inadequate. The federal view, with immediate imputation, became the standard Reformed position.

The Reformed & Confessional Position

The Westminster Confession confesses both elements of original sin and grounds them in Adam’s headship:

“They being the root of all mankind, the guilt of this sin was imputed; and the same death in sin, and corrupted nature, conveyed to all their posterity descending from them by ordinary generation.” (WCF 6.3)

And the resulting corruption:

“This original corruption, whereby we are utterly indisposed, disabled, and made opposite to all good, and wholly inclined to all evil, doth in this life remain in those that are regenerated; and although it be through Christ pardoned and mortified, yet both itself, and all the motions thereof, are truly and properly sin.” (WCF 6.4–5)

The Shorter Catechism names the sinful estate’s elements:

“The sinfulness of that estate whereinto man fell, consists in the guilt of Adam’s first sin, the want of original righteousness, and the corruption of his whole nature, which is commonly called original sin; together with all actual transgressions which proceed from it.” (WSC 18)

And it explicitly affirms Adam’s federal headship as the ground of imputation:

“The covenant 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.” (WSC 16)

The Larger Catechism adds the same in fuller terms (WLC 22, 25–26). The Standards thus confess: guilt imputed, righteousness lost, nature corrupted, all proceeding from Adam as covenant head — and that even in the regenerate the remaining corruption is “truly and properly sin.”

Contrasting Views

Pelagianism denies original sin altogether: no guilt is imputed and no corrupt nature inherited; each soul is created innocent, and sin spreads only by imitation. Semi-Pelagianism admits inherited weakness but denies inherited guilt and preserves the will’s power to begin turning to God.

Roman Catholicism affirms original sin as the loss of original righteousness, but teaches that concupiscence remaining after baptism is not properly sin, and that baptism removes the guilt of original sin, thereby weakening both its persistence and its gravity. Arminianism typically denies the immediate imputation of Adam’s guilt, holding that we inherit corruption but are not personally condemned for Adam’s sin until we ratify it by our own; universal prevenient grace then counteracts inherited inability. Mediate imputation (de la Place) holds we are accounted guilty only because we are corrupt — reversing the biblical order, which makes guilt the ground, not the result, of corruption. Against all these, Scripture teaches that we are condemned in Adam by his one trespass and corrupted in our whole nature, so that we are guilty before we act and sinful before we choose.

Connections to Other Loci

Original sin is the heart of Hamartiology, presupposing the covenant of works and the fall from Anthropology. It is the foundation of total depravity and inability, since the corrupt nature is the source of all actual sin and the reason for the bondage of the will. It is bound to Soteriology, for the imputation of Adam’s sin is the exact counterpart of the imputation of Christ’s righteousness in justification (Rom. 5:18–19). It bears on Christology, since Christ, conceived by the Holy Spirit, was free from original sin and so a fit Savior; and on the sacraments, for infant baptism testifies that even infants need cleansing from sin. It also touches the doctrine of God’s justice, vindicating the righteousness of his condemnation of all in Adam.

Christ & the Gospel at the Center

The doctrine of imputation is the bridge from ruin to redemption. The very principle that condemns us in Adam saves us in Christ. As Adam’s one disobedience was imputed to all in him, bringing condemnation, so Christ’s one act of obedience is imputed to all in him, bringing justification and life (Rom. 5:18–19). Christ is the last Adam, the new federal head, conceived without sin and untainted by Adam’s corruption, who stood where Adam fell. United to him by faith, the believer receives a double remedy: the guilt of original and actual sin pardoned through his blood, and his perfect righteousness reckoned as our own. Thus the doctrine of original sin, far from leaving us in despair, points us straight to the gospel: condemned by another’s act, we are saved by Another’s act, and the same God who justly imputes Adam’s sin graciously imputes Christ’s righteousness.

Pastoral & Practical Significance

This doctrine teaches us deep humility, for our sinfulness reaches back before our first choice; we are sinners by nature, not merely by deed. It cuts off all boasting and self-salvation, for we cannot fix what we did not create and cannot escape what we inherited. It explains the sin we find within ourselves even after conversion, for original corruption remains in the regenerate, summoning us to lifelong mortification. It assures parents that the gospel is needed by their children from birth, and it grounds the comfort of covenant baptism. Above all, it drives us to Christ, the second Adam, in whom alone our guilt is pardoned and our nature renewed. The believer who grasps original sin will neither despair of his sin nor presume upon his merit, but rest wholly in the imputed righteousness of his covenant Head.

Key Terms

• Original sin — the inherited guilt and corruption from Adam.
• Imputation — the legal reckoning of one’s guilt or righteousness to another.
• Immediate imputation — Adam’s guilt charged directly to his posterity.
• Mediate imputation — the (rejected) view that guilt follows from inherited corruption.
• Inherited corruption — the polluted nature conveyed from Adam.
• Concupiscence — disordered desire; in Reformed teaching, truly sin.
• Federal headship — Adam’s representative standing for his posterity.

Key Scripture References

• Genesis 5:3 — Adam fathered a son in his own likeness.
• Psalm 51:5 — conceived in sin.
• Job 14:4 — no clean thing from an unclean.
• John 3:6 — that which is born of the flesh is flesh.
• Romans 5:12–21 — Adam’s one sin imputed to all, paralleled with Christ.
• 1 Corinthians 15:22 — in Adam all die.
• Ephesians 2:3 — by nature children of wrath.

Further Study

• Westminster Confession of Faith 6.1–6; Shorter Catechism Q. 16–18; Larger Catechism Q. 22, 25–26
• John Murray, The Imputation of Adam’s Sin
• John Calvin, Institutes, Book II.1
• Herman Bavinck, Reformed Dogmatics, Volume 3
• Francis Turretin, Institutes of Elenctic Theology, Ninth Topic
• Charles Hodge, Systematic Theology, Volume 2, on original sin