by Steven B. Cowan

The Medieval period in Western history (roughly A.D. 400-1600) was dominated by Christianity. Most people in Europe claimed allegiance to the Christian faith, and the ideas of the Christian worldview permeated society at every level. Even the discipline of philosophy was conducted within the parameters of Christian thought. Philosophers did their scholarly work guided by the following convictions:1


  • One, omnipotent God (the God of the Bible) existed and created the universe out of nothing.
  • The one God existed in three eternal persons—Father, Son, and Holy Spirit.
  • The Son of God became incarnate in the God-Man Jesus who died for sins, was resurrected, and ascended into heaven.
  • Salvation is possible only through God’s grace.
  • Those who believe in Jesus Christ are alone the recipients of God’s grace and will enjoy the blessing of eternal life.


Anselm of Canterbury was one such philosopher. He was born in 1033 in Aosta, Burgandy (northern Italy). He entered the Benedictine monastery at Bec in 1060 at the age of 27.  In 1078 he became the Abbot of the monastery. Fifteen years later, in 1093, he moved to England to become the Archbishop of Canterbury. He died in 1109 at the age of 76.  During this time Anselm wrote many theological and philosophical works explaining and defending Christian doctrine.

In all of his philosophical work, Anselm was guided, like his predecessor Augustine, by the principle “faith seeking understanding.”  For Anselm, the Christian philosopher does not leave his religious convictions on the shelf when doing his philosophizing.  Rather, he takes the Christian faith as his starting point and seeks to clarify its meaning and significance and defend its truth-claims against objections.  Anselm displayed this approach when he dealt with the two apologetic issues for which he is best known. First, he provided the first systematic defense of the penal substitutionary view of the atonement. Second, he developed the ontological argument for God’s existence.


Anselm on the Atonement

In Anselm’s day, Islam was on the rise.  And Islam had their own apologists for their religion.  One of the objections that Muslims made (and still make) to Christianity is that it would be unfitting, undignified, even absurd for God to become a man as Christians believed.  Responding to this objection was one of the motivating factors that led Anselm to write his famous treatise Cur Deus Homo? (Why Did God become Man?).  The answer Anselm gave, in short, is that God became man because it was the only means by which sinful man could be reconciled to a holy God.

Muslims claim that God needs no atonement in order to forgive sin.  He can simply decide to forgive sin at will.  Anselm’s argument is designed to refute this claim and show that God rightly requires a satisfaction for our sin.  And it is this requirement for satisfaction that explains why it is fitting and rational that God become a man.

Anselm defines sin as “not to render to God his due.”  And what human beings owe to God is a life of perfect obedience to his will.  Of course, we have failed miserably in this regard.  We have not given God his due.  Which means that we owe God a debt that we cannot pay.  As John Stott puts it, “Our present obedience and good works cannot make satisfaction for our sins, since these are required of us anyway.”2 Anselm concludes that “there is no one. . .who can make this satisfaction except God himself. . . .But no one ought to make it except man.”  If man is to be saved, the only solution is for God to become a man and make the required atonement for our sins.

Today we might quibble with some of the details of Anselm’s account, but it is a clear and inspiring attempt to do justice to the biblical data concerning the incarnation and atonement of Jesus.


Anselm on God’s Existence

In his writings, Anselm constructed more than one argument for God’s existence.  But, what many consider his crowning achievement is the argument known today as the ontological argument (from Gr. ontos, “being”).  According to his own testimony in his work Proslogion, Anselm desired to find a short and simple argument “to demonstrate that God truly exists.”3 Though novice readers sometimes find his argument difficult to understand, it is really the paradigm of simplicity.  The argument begins with Anselm offering a brief definition of what we all understand and believe about the term “God.” God is a “being than which no greater can be conceived.”4 Today, we might paraphrase this to say that God is the greatest conceivable being.  Everyone understands what we mean by this expression and thus has an idea of God, says Anslem, even the fool who says in his heart, “There is no God” (Ps. 14:1).  Anselm then presented this argument:

Hence, even the fool is convinced that something exists in the understanding, at least, than which nothing greater can be conceived. For, when he hears of this, he understands it. And whatever is understood, exists in the understanding. And assuredly that, than which nothing greater can be conceived, cannot exist in the understanding alone. For, suppose it exists in the understanding alone: then it can be conceived to exist in reality; which is greater.

Therefore, if that, than which nothing greater can be conceived, exists in the understanding alone, the very being, than which nothing greater can be conceived, is one, than which a greater can be conceived. But obviously this is impossible. Hence, there is no doubt that there exists a being, than which nothing greater can be conceived, and it exists both in the understanding and in reality.5


Basically, what Anselm does here is ask us to conduct a thought experiment. He asks us to suppose that God—the greatest conceivable being—exists merely as an idea in our minds. In that case, however, it would turn out that we could conceive of a being greater than the greatest conceivable being, namely, one that exists in reality, too. But, by definition, it is impossible for there be a being greater than the greatest conceivable being. Hence, God must exist in reality as well as in the mind.  Anselm is arguing, in other words, that to deny the existence of God is self-contradictory.  Therefore, it follows that God really exists.

Some scholars have argued that Anselm did not intend this argument to be a proof for God’s existence meant to convince unbelievers, but simply an explanation of what the faithful already believe about God.6 As indicative of this interpretation, it is pointed out that Anselm begins his argument with a prayer to God.  The prayer notwithstanding, this interpretation is hard to square with what Anselm actually says about his argument.  We already noted above that Anselm believes that the argument demonstrates God’s existence.  Moreover, after presenting the argument, Anselm remarks,

There is, then, so truly a being than which nothing greater can be conceived to exist, that it cannot even be conceived not to exist; and this being you are, O Lord, our God. . . . Why, then, has the fool said in his heart, there is no God (Psalm xiv. 1), since it is so evident, to a rational mind, that you do exist in the highest degree of all? Why, except that he is dull and a fool?7

It seems clear that Anselm expects any rational mind to see the cogency of his argument and believe that God exists.

The ontological argument has had many critics over the years, and some of the criticisms have persuaded the majority of thinkers to conclude that it fails to truly demonstrate God’s existence as Anselm claimed.8 Yet, the spirit of Anselm’s argument lives on as more recent attempts have been made to offer new versions of the argument that avoid whatever difficulties Anselm’s original argument may have.9




Whether or not Anselm’s arguments for the atonement or the existence of God are successful in the form he presented them, he nevertheless provides Christians today with a role model for doing apologetics.  He held to his faith with firm and passionate conviction while seeking to use his God-given intellectual skills to articulate and defend the faith in a way that confirmed and strengthened the faith of believers and silenced the careless objections of the foolish unbeliever.


Steven B. Cowan is the editor of Areopagus Journal and Associate Professor of Philosophy and Apologetics at Southeastern Bible College in Birmingham, Alabama.




1 The following points are adapted from Julius R. Weinberg, A Short History of Medieval Philosophy (Princeton University, 1964), 25-26.

2 John R.W. Stott, The Cross of Christ (Downers Grove, IL: InterVarsity, 1986), 119.

3 Anselm, Proslogion, Preface.

4 Ibid., II.

5 Ibid.

6 See, e.g., Karl Barth, Anselm: Fides Quaerens Intellectum (SCM Press, 1960).

7 Anselm, Proslogion, III.

8 For a discussion of most of the attacks on the argument, see Stephen T. Davis, God, Reason, and Theistic Proofs (Grand Rapids: Eerdmans, 1997), 15-45; and Alvin Plantinga, God, Freedom, and Evil (Grand Rapids: Eerdmans, 1974), 85-104.

9 See, e.g., Alvin Plantinga, God, Freedom, and Evil, 104-112.