The debate over the will between Augustine and Pelagius focused mainly on the doctrine of original sin and the nature of the grace needed for humans to lead lives of faith and holiness.


Pelagius and Augustine were two of the first figures in early Christianity to debate the nature of the human will after the fall of Adam and Eve and the nature of the grace needed to allow humans to exercise faith. Pelagius argued that the sin of Adam, called original sin, was in no way passed down or imputed to the rest of the human race. Adam and Eve simply provided a bad example that was followed by all of their offspring. Because of this belief, Pelagius believed that grace simply helped humans to know what to do to live holy lives and that humans were completely capable of following these commands. Augustine, on the other hand, argued that the sin of Adam affected the will of every human who followed, rendering them incapable of following God’s commands or loving God. Because of this, the grace of God is not simply illuminatory but liberates the will and enables it to love and obey God.

One of the most important debates in church history is that between Pelagianism and Augustinianism. As you might have guessed, these labels represent two figures: Pelagius and Augustine, both of whom lived in the fourth and fifth centuries. The debate was complex and, much like an onion, had layer upon layer. But its main facets concerned the nature of man and the necessity of divine grace.


Pelagius was serious about piety. His zeal made itself known in his monastic devotion. His passion for godliness manifested itself in his efforts to bring about moral reform. That in itself may sound like a praiseworthy cause, but when motivated and driven by a theology that placed considerable emphasis on man’s natural abilities, it proved controversial to say the least.

Rejection of Original Sin

Let’s start with sin, specifically original sin, the belief that Adam’s guilt and corruption are inherited by and transmitted to all mankind. Pelagius rejected original sin, affirming that Adam sinned for himself and himself alone. His guilt and corruption were not transferred or imputed to humankind when he sinned. Rather, Adam only set an unfortunate and regrettable example. Those who came after Adam saw their father’s example and followed in his footsteps, imitating his disobedience to God. That is how sin has continued to this day.

By rejecting the power and bondage original sin brings, Pelagius gave enormous power to man’s will even after the fall. According to Pelagius, man’s will is not inclined toward sin, nor is it controlled by sin, as if man’s inclinations have been polluted by Adam. Man’s will is not enslaved to a depraved Adamic nature, as if he is incapable of doing works that merit righteousness. It is free, just as free after Genesis 3 as before.

You can imagine, then, Pelagius’ outrage when he read Augustine’s prayer in Confessions, “Give what you command; command what you will.” That prayer implies man’s inability and dependence on God, as well as man’s great need for God’s grace to do the very thing God has commanded him to do. Not so, said Pelagius, for if God gives a command—and such commands pervade the Scriptures—man must be able and capable in and of himself to perform such a command. God would never command man to do something man could not do.

Redefining grace and the work of Christ

If man’s will is as free as Pelagius thinks, then is divine grace necessary? The short answer is “no.” God’s grace can and does assist the sinner, but technically it is not actually necessary. If it were, then man’s freedom would be undermined; man would not be responsible for his actions. Man must be equally able to choose that which is good as he is able to choose that which is evil. If God must help the will along, then man is not really free.

Denying the necessity of grace influenced the way Pelagius understood God’s call and even grace itself. When Scripture refers to God’s calling those whom he predestined (Rom. 8:28–30), Pelagius said in his Commentary on Romans that Paul merely means God “gathers together those who are willing, not those who are unwilling.” Naturally, Pelagius defined grace not as something supernatural, efficacious, irresistible, or necessary. Instead, by grace Pelagius meant that which reveals to man right from wrong, giving him further illumination concerning his obligations to obey the law of God and follow the example of Christ. Christ did not come to atone for our guilt but to set us a moral example to follow, by which we can attain heaven. In and of himself man is capable of doing just that. This means Pelagius believed in monergism, salvation being worked wholly by one party—but he did not believe in a divine monergism but a human monergism.

Although Pelagius had a number of devoted followers, many of whom were more articulate and persuasive theologically than Pelagius himself (e.g., Caelestius, Julian of Eclanum), his views were condemned by several councils (Carthage and Mileve in 418 and Ephesus in 431).


As mentioned already, Pelagius despised Augustine’s prayer in his Confessions because that prayer expressed the Christian’s utter dependence on God to do what God commanded. Pelagius’s views became apparent in his own books, On Nature and On Free Will. But Augustine would not remain silent forever. At first, he responded to Caelestius but in 415 Augustine responded to Pelagius himself in his book On Nature and Grace. An entire anti-Pelagian corpus followed as well.

The Hinge of the Debate: Original Sin and the Captivity of the Will

Augustine’s writings reveal that the whole debate hinged on Pelagius’s rejection of original sin. For as long as man was considered free from sin’s grip, grace would never be necessary. Augustine put forward an extensive defense of original sin, exegeting passages like Psalm 51 and Romans 5. Augustine demonstrates that humankind has been affected by Adam’s guilt and corruption. The result? “There is none who seeks after God” (Rom. 3:11).

Furthermore, original sin is not limited to part of humanity but is universal in its reach. Nor did original sin only affect part of man, but its poison has spread to every aspect of man. No part of man’s nature has escaped. And that means man’s will, too, falls under sin’s curse.

Prior to the fall, man’s will was not in slavery to sin. It was capable of choosing that which was good. Sin was merely a possibility. But after the fall, man’s will changed. Polluted by sin, what was merely a possibility now became a necessity. Augustine described this shift with the following Latin phrases:

  • posse peccare—prior to the Fall man has the ability to sin
  • posse non peccare—prior to the Fall man has the ability not to sin

But after the Fall…

  • non posse non peccare – man is not able not to sin

Man still possesses moral agency after the fall (necessity to sin does not preclude his culpability), but after the fall his moral agency is necessarily inclined toward sin and evil. It’s not just that he cannot choose that which is pleasing to God, he will not. His bondage is a willful bondage. Or as Augustine put it, after the fall man possesses a captive free will (liberum arbitrium captivatum). It is only by God’s grace that he possesses a liberated free will (liberum arbitrium liberatum). Needed, then, is a grace so powerful and effective that it can set free a will enslaved to sin. Grace is necessary, and not just any grace but a grace that can set the enslaved will free.

Liberating Grace Necessary

This type of grace must look different than the grace Pelagius put forward. It is not a grace that merely illuminates or educates the mind, making the sinner aware of Christ’s example. That type of grace is the law in disguise, for what sinner can do what Christ did? Needed instead is a grace that does not merely enlighten but regenerates, a grace that works within the depraved sinner to bring about a new nature.

When Augustine came to a text like Romans 8:28–30 or John 6:45, he did not say as Pelagius did that God merely “gathers together those who are willing, not those who are unwilling.” That not only misinterprets Paul and Jesus but fails to consider how deep are the effects of original sin, so deep that man’s will cannot escape. Instead, says Augustine citing John 6:45, “everyone who has learned from the Father not only has the possibility of coming, but actually comes!” (On Rebuke and Grace). The Father calls his elect to his Son and it is a call that is both particular and efficacious. Anything short of gratia irresistibilis (irresistible grace) will fail to liberate the will whose master is sin, the world, and the devil.

Faith: A Gracious Gift

Furthermore, teaches Augustine, even the faith through which man trusts in Christ must be considered a gracious gift from God—gratia dei gratuita. Man cannot even claim to initiate faith; the beginning of faith (initium fidei) is divine in its origin. Unless God grants faith in the first place, man will never believe but remain in his stubborn, willful disbelief.

Turning to the apostle Paul (Eph. 1:13–16; Phil. 1:28–29; 1 Thess. 2:13), Augustine concludes that grace merely extended or offered is insufficient because man does not desire it, his willful bondage being what it is. Needed instead is a faith God does not merely make possible but actual by working it within. “The will itself is something God works in us,” says Augustine in Revisions. Does that mean God coerces the unbeliever? Not at all. Its irresistible power lies in its “ineffable sweetness,” says Augustine in The Grace of Christ and Original Sin.

The Pelagian Debate: Prophetic

Augustine’s defense of original sin and the necessity of grace proved crucial for the church during Augustine’s time. But it also proved instrumental for a future era: the Reformation. Pelagianism may have been technically rejected by Roman Catholic theologians but at a popular level it had taken root among the masses.

Yet when reformers like Martin Luther and John Calvin returned to the Scriptures with Augustine by their side, the gratuity of God’s grace liberated them from a system of works. As a result, they were awakened by the rediscovery of sovereign grace and mounted pulpits with liberating news for captive sinners. No mere moral reform followed but a reform in doctrine and doxology.

Further Reading

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