A Brief Survey of Anselm of Canterbury's Cur Deus Homo?
© 1994, Scott David Foutz

Outline Of This Paper
I. Introduction
II. Arguments
A. Anthropology
1. Purpose of Reason
2. The Perfect Number
B. Hamartiology
1. Feudal Law
2. Honor of God
C. Soteriology
1. Contra Ransom Theory
2. Satisfaction/Punishment
D. Christology
1. Necessity of the God-Man
2. Due/Undue Obedience
3. Infinite Merit
III. Critique

Introduction to the Treatise

Anselm (1033-1109), archbishop of Canterbury was the first to set forth a systematic argument for the necessity of Christ's atoning death on the cross. His Cur Deus Homo? (1094-1098) attempted to provide rational explanations for the Christians belief in the atonement in dialectic form. The treatise presents a discussion between Anselm and one Boso (abbot of Bec; 1124-1136), with whom Anselm had much contact and correspondence, and who is said by Anselm to be "the one who among the rest presses me more urgently to debate with me," (Cur, I.1). Anselm seeks to respond to "many earnest requests that I should commit to writing the proofs of a particular doctrine of our faith," namely: "For what reason or necessity did God become man and, as we believe and confess, by his death restore life to the world, when he could have done this through another person (angelic or human), or even by a sheer act of will?" (I.1)

Cur Deus Homo? is divided into two books, the first of which "contains the objections of unbelievers who reject the Christian faith because they regard it as contrary to reason, along with the answers of believers. It ends by proving by necessary reasons (Christ being put out of sight, as if nothing had ever been known of him) that it is impossible for any man to be saved without him. In the same way, as if nothing were known of Christ, it is shown in the second book, by equally clear reasoning and truth, that human nature was created in order that hereafter the whole man, body and soul, should enjoy a blessed immortality. It is proved that it is necessary for this purpose for which man was made to be achieved, but only through a Man-God, and so that all the things we believe concerning Christ must necessarily take place." (Cur, Preface)

Book One consists of twenty-five chapters, and Book Two of twenty-two. Anselm himself provided the chapter headings for the sake of further clarification of each chapter's contents. Therefore, this paper will not present an outline of the treatise's content. Instead, various prominent elements of Anselm's argument and theology will be examined. The paper will conclude with a brief critique of Anselm's work.

The Argument of Cur Deus Homo?

Anthropolgy: The Role of Rational Nature

Anselm made quite significant contributions to the medieval church's understanding of Christian anthropology through such works as De conordia praescientiae, and Monologian. In Cur Deus Homo?, Anselm confines his discussion of anthropology to the discussion of the purpose of man's existence, and the role which man must ultimately play in the divine plan of God.

Anselm sees divine purpose in the fact that God has bestowed man with the faculty of reason. This reason or rational nature was "created just by God, so that it might be blessed in the enjoyment of him" (II.1). The purpose of the reason is to enable man to distinguish between the just and unjust, between good and evil. But this rational nature is not to be seen as a neutral faculty through which either good or evil may be chosen. Instead, the reason was originally disposed toward the good, or as Anselm puts it, "the rational nature was created to love and choose the supreme good above all things," (Ibid.). Anselm cites the perfection of all of God's designs as proof that reception of such a faculty points to the fact that man was intended to attain that which he sought, namely, the supreme good, that is, God. In other words, God granted rational nature to Adam with the intent that in the fulness of time, Adam would be blessed with an eternal enjoyment of God.

According to Anselm, the achievement of this eternal enjoyment was to play a grander part in God's overall design. "When man was created in paradise without sin, he was set, as it were, by God between God and the devil, in order to overcome the devil by not consenting to his persuasions to sin. This would have vindicated and honored God and confounded the devil, since man, though the weaker, would have refused to sin on earth at the instance of that very devil who, though the stronger, sinned in heaven without persuasion." (II.22)

Man was to be the means through which God demonstrated the devil's weakness and man's superior ability to obey. But this was not realized in Eden, due to Adam's fall from grace. Does this then leave the divine plan of God thwarted? Anselm does not believe so. Since God so purposed such a destiny for man from the beginning, such a destiny must still exist. Somehow man must achieve both perfect obedience to God while demonstrating his superiority of obedience over the devil. The answer to how this can be achieved will be postponed until Anselm's Christology is discussed.

Brief mention should be made regarding Anselm's epistemology. Anselm views the particulars and phenomena as dependent upon universals grounded in the mind of God. An example of this is seen above in the fact that Anselm bases upon the fact that men possess rational natures that God must indeed have a divine purpose from which this possession is derived (namely, to eternally enjoy God's presence). In addition, this purpose, being grounded in the perfect will of God, is unchangeable, enabling Anselm to confidently assert that men must necessarily achieve this purpose, even if it means that God Himself must accomplish it for man (through the work of a Man-God). This epistemology (referred to a "Realism", though differentiated from that of modern discussions) provides the structural backbone to Anselm's reasoning.


Central to Anselm's argument is his understanding of sin. Anselm sees the duty of every rational creature as subjecting every inclination to the will of God. Of this Anselm writes, "This is the debt which angels and men owe to God. No one who pays it sins; everyone who does not pay it sins. This is the sole and entire honor which we owe to God, and God requires from us. One who does not render this honor to God takes away from God what belongs to him, and dishonors God, and to do this is to sin. Moreover, as long as he does not repay what he has stolen, he remains at fault." (I.11)

Anselm's belief that all sin stems from a violation of God's inherent honor forms the backbone of his theory of atonement. Much has been written on the subject of where Anselm derived his understanding of sin. Many explain Anselm's unique perspective as a result of medieval society's shift in its understanding of justice from that of Roman law to a feudal system. Erickson writes, "...The feudal system was the most powerful force in the structuring of society. Justice and law had become more of a personal matter; violations of the law were now thought of as offenses against the person of the feudal overlord... In matters of private offense, various forms of satisfaction could be substituted for punishment. By Anselm's time the concept of satisfaction had become an integral part of the feudal structure... Anselm pictures God as a feudal overlord who, to maintain his honor, insists that there be adequate satisfaction for any encroachment on it," (797; emphasis mine).

But Anselm's understanding may go much deeper than a mere transference of theology onto fuedal justice theory. For in his insistence that sin is a violation of God's honor, Anselm, in effect, grounds the reality of sin to the character of God. Such a structure automatically disallows the possibility that "sin" is merely a governmental or arbitrary standard imposed by God on mankind. Anselm then uses this understanding of sin's utter reality as the foundation for his entire soteriology. If sin is indeed a reality in relation to the character of God, then God will be moved to respond to man's guilt of sin.


Anselm deliberately refutes the predominant atonement theory of his day, the Ransom theory developed by Origen and Gregory of Nyssa. The Ransom theory proposed that prior to the atonement, the devil had the "right of possession" over men due to their falleness. The death of Christ then served as a ransom for our rescue, with the devil believing that he had swapped mankind for the crucified second Person of the Trinity. But Satan was ultimately deceived by assuming that Christ could be held by death.

In chapter seven of Book One, Anselm refutes the claim of the ransom theorists that God owed the devil anything. He writes, "I cannot see what force this argument has. If the devil or man belonged to himself or to anyone but God, or remained in some power other than God's, perhaps it would be a sound argument. But the devil and man belong to God alone, and neither one stands outside God's power; what case, then, did God have to plead with his own creature, concerning his own creature, in his own affair, unless it was in order to punish his servant, who had persuaded his fellow servant to desert their common master?"

Instead of the ransom theory, Anselm sets forth what has come to be known as the Satisfaction or Commercial Theory. As stated earlier, Anselm's soteriology rests upon his understanding of sin, namely, that sin is a violation of the honor of God. What then is to be done to vindicate such a violation? Anslem claims that God has two choices: punishment and satisfaction. Punishment would restore honor to God through the removal of freedom or ability from the individual, and through demonstrating God's sovereignty. Satisfaction restores God's honor through the individual's payment to God, first, in full, and then above and beyond the debt incurred. The fact that sin is rooted in a violation of God's character necessitates a response by God in either of these two methods of vindication. Anselm writes, It does not belong to [God's] freedom or kindness or will to forgive unpunished the sinner who does not repay to God what he took away," (I.12).

It should be remembered that the purpose of Anselm's treatise is to demonstrate the necessity of Christ's death on the cross. Therefore, the punishment option must be shown to be not possible, since God ultimately chose the mode of ssatisfaction. Anselm does this by adopting an argument proposed by Augustine which claims since some of the angels had fallen from grace, there must then be at least as many men who are restored, since the original appointed number of individuals who will occupy the "heavenly city" must not waver. "We cannot doubt that the rational nature, which either is or is going to be blessed in the contemplation of God, was foreseen by God as existing in a particular reasonable and perfect number, so that its number cannot be greater or smaller... Either [the fallen angels'] number must necessarily be made up, or else the rational nature will remain incomplete in number, although it was foreseen in a perfect number; but this cannot be." (I.16) (The reader may again take note of the fact that (Augustine and) Anselm's argument here employs [medieval] Realism.)

The only reasonable choice left for God (based on his will to have the perfect number of rational natures) between punishment and satisfaction is that of satisfaction. As stated above, satisfaction consists of both the full payment of the debt and a gift whereby the debt is exceeded. The debt in this instance which must be repaid in full is that honor which was taken from God when man failed to obey God fully and thereby shame the devil by demonstrating that the weaker creature could persevere in obedience to a greater degree than the stronger.

But now that man has fallen into disobedience, how may he ever regain his original state of innocence within which he was called to persevere. Indeed this in itself is an impossible task!. Regarding a payment in excess of the debt, who has possession of that which exceeds the tremendous debt incurred? Since all of creation has now fallen, that which must be given must exceed all of creation in greatness. Anselm writes, "If he is to give something of his own to God, which surpasses everything that is beneath God, it is also necessary for him to be greater than everything that is not God. But there is nothing above everything that it not God, save God himself... Then no one but God can make this satisfaction," (II.6).


It is clear from Anselm's argument (and any reasonable consideration) that man has no hope of satisfying the vindication required by the violation of God's honor. But all is not lost for mankind, for this leaves open only one possible solution: "If then, that celestial city [i.e., the perfect number of rational natures] must be completed from among men, and this cannot happen unless the aforementioned satisfaction is made, while no one save God can make it and no one save man ought to make it, it is necessary for a God-Man to make it." (Ibid.) Anselm concludes that the dire predicament of man necessitates the work of a God-Man who alone is able to achieve the task which is being required of man.

In his following description of this necessary God-Man, Anselm maintains a Chalceonian christology through emphasizing the need of two natures within one person: "If these two complete natures are said to be united in some way, but still man is one person and God another, so that the same person is not both God and man, the two natures cannot do what needs to be done. For God will not do it, because he does not owe it, and man will not do it, because he cannot. Therefore, for the God-Man to do this, the person who is to make the satisfaction must be both perfect God and perfect man, because none but true God can make it, and none but true man owes it." (II.7) Anselm then goes on to describe the fittingness whereby this perfect God should be the second Person of the Trinity (II.9), and that the perfect man should be born of a virgin woman (II.8).

This God-Man then proceeds to live a perfect life upon earth despite the persuasions of the devil, just as Adam was originally intended. To live thus is the duty of all men, and therefore, in the case of the God-Man, secures no special grace from God. Rather it is payment of the first portion of the satisfaction, namely, payment in full of the debt incurred: "If we say that he will give himself to obey God, so that in steadfastly maintaining justice he submits himself to his will, this will not be to give what God does not require of him as an obligation. For very rational creature owes this obedience to God." (II.11).

The question is then raised regarding what this God-Man might give in order to pay the full satisfaction. Anselm begins his answer by pointing out that since "mortality belongs to the corrupt, not to the pure nature of man," (Ibid.), it follows that this sinless God-Man "will not be obliged to die," (II.10). As to whether or not it will even be possible for the God-Man to die, Anselm writes, "As he will be God, he will also be almighty. Then if he wills it he will be able to lay down his life and take it again... If he wills to permit it, it will be possible for him to be killed, and if he does not will it, it will not be possible," (II.11).

This freedom to lay down his life and take it up again, based on his willing it, opens the door to a possible way to fully pay the satisfaction. Anselm continues, "Nothing that man can suffer for God's honor, freely and not as an obligation, is more bitter or harder than death. Nor can a man give himself more fully to God than he does when he surrenders himself to death for His honor. Then he who wishes to make satisfaction for man's sin must be able to die if he wills it," (II.11). The greatest act of honor which a man can do for God is to lay down his own life in order to protect that honor. Since death is not an obligation upon sinless men, this act, when performed by the sinless God-Man, would suffice to exceed in payment the original debt.

This then, being the only feasible method whereby mankind may be relieved of its debt and restored to its intended purpose, becomes, in Anselm's argument, proof of its reasonableness, necessity and truth. In this way Anselm presents the necessity of Christ having to die upon the cross for the sake of mankind.

How can this act secure the forgiveness of such a great multitude of sins? The answer lies in the fact that this evil is committed against the very Person of God. [Boso:] "A sin committed against [the God-Man's] person is incommensurate with every conceivable sin that does not touch his person. [Anselm:] We see, then, that no greatness or multitude of sins apart from God's person can be compared to an injury done to the bodily life of this Man." (II.14) The fact that such an experience as the God-Man underwent is unparalleled in its gravity due to the Person against whom it is being committed results in a likewise unparalleled merit toward the willing and unobliged participant. It is through this willing obedience that the act of the God-Man secures infinite merit in the sight of God.

What then, did the God-Man objectively achieve through a willing death? The answer is two-fold. Firstly, he demonstrated to all men the degree to which obedience is owed God. "Do you not understand that by enduring with gentle patience the injuries and insults and death on the cross with thieves, all brought on him by his obedience in maintaining justice, he gave an example to men, to teach them not to turn away from the justice they owe to God on account of any trials they can experience?" (II.18) This owed obedience which resulted for the God-Man in suffering and humiliation is to be a sign to men that obedience should and must be maintained despite seemingly adverse consequences.

The fact that this owed obedience resulted in a death which the God-Man was not obliged to undergo (due to his sinlessness), provides men with an example of willfull surrender of their own lives which they know are obliged to suffer death. "This Man freely offered to the father what he would never have lost by any necessity, and paid for sinners what he did not owe for himself. Therefore he gave us a more striking example, to the effect that each man should not hesitate to surrender to God for himself, when reason demands it, what he is going to lose very soon." (Ibid.)

Secondly, the fact that the God-Man willingly underwent such grave injustice in order to pay in full the satisfaction results in the necessity that God reward the Son. But the Son, being God himself, is in need of no thing nor lacks anything. "What then, will be given him as a reward, when he is in need of nothing and there is nothing that can be given or forgiven him?" (II.19) The hope of man lies in the fact that the Son is free to give the reward to whomever he pleases and the Father will be obliged to give it since it is the Son's to do with as he pleases. Anselm concludes, "To whom would it be more fitting for him to assign the fruit and recompense of his death than to those for whose salvation (as truthful reason has taught us) he made himself man, and to whom (as we have said) by dying he gave an example of dying for the sake of justice?... Or whom will he more justly make heirs of the debt which he does not need, and the abundance of his own fullness, than his kinsmen and brethren, whom he sees bound by so many great debts, languishing in poverty and deepest misery, so that what they owe for their sins may be forgiven them, and what they need, on account of their sins, may be given them?" (II.19)

In Anselm's view, Christ passes on to mankind the infinite merit which he accomplished in his work on the cross. This merit then restores mankind in the sight of God, enabling the original purpose of God to be fulfilled, namely, that man as a rational creature may eternally enjoy contemplation of God's presence.

Some scholars criticize Anselm on several grounds which we can only briefly mention here. First, as mentioned above, many see an over-dependence by Anselm upon medieval justice theory. Secondly, Anselm makes no mention of any "penalty" for sin. Berkhof writes, "This theort really has no place for the idea that Christ by suffering endured the penalty of sin, and that His suffering was strictly vicarious. The death of Christ is merely a tribute offered voluntarily to the honor of the Father," (Theology, 386). A third criticism is aimed at Anselm's lack of discussion regarding in what manner Christ's infinite merit is passed on to man. "[Anselm's Satisfaction theory] represents the application of the merits of Christ to the sinner as a merely external transaction. There is no hint of the mystical union Of Christ and believers." (Berkhof, History, 174) "There is no hint of the mystical..., nor of faith as accepting the righteousness of Christ. Since the whole transaction appears to be rather commercial, the theory is often called the commercial theory." (Theology, 386)

A final problem which may face contemporary readers of Anselm may well be the entire epistemology under which the author constructs his argument. It is true that most readers have not consciously chosen under which epistemology they will operate. Often an eclecticism is probably employed. But in reading Cur Deus Homo?, one cannot help but become aware of a foreignness to a reasoning which claims the necessity of a certain number of rational natures to occupy heaven, and for man to necessary possess rational contemplation of God due to the fact that Edenic Adam was given a chance.

I must admit that I question this epistemology, and yet am the first to admit that Anselm would surely be appalled at the degree of relativism which he would find in my own reasoning, as a mere by-product of my existence within contemporary American culture. To me, this is the major issue facing Anselm's relevance to today's world. And yet, the author of this paper is in no way prepared to construct any conclusion on this matter. Let it merely be said that Anselm presents a very viable demonstration of the necessity for the gospels' account of Christ's work, and that contemporary students would do well to learn from both its content and methodology.


Anselm of Canterbury. Cur Deus Homo? In A Scholastic Miscellany: Anselm to Ockham.

Fairweather, Eugene R. ed. (Philadelphia: Westminter Press; 1956): 100-183.

Berkhof, Louis. The History of Christian Doctrines. (Grand Rapids: Baker Book House;


........Systematic Theology. (Grand Rapids: Eerdmens Publ.; 1941)

Erickson, Millard J. Christian Theology. (Grand Rapids: Baker Book House; 1985)

Horne, Charles M. The Doctrine of Salvation. (Chicago: Moody Press; 1984)