The Nature and Necessity of the Cross: Why Christ Had to Die for Sin (With a Little Help from Anselm)


For there is one God, and there is one mediator between God and men,
the man Christ Jesus, who gave himself as a ransom for all,
which is the testimony given at the proper time.
— 1 Timothy 2:5–6 —

Yesterday (Psalm Sunday) marked the day when Jesus entered Jerusalem en route to a cross. There on that Roman instrument of death, he revealed God’s justice and mercy, disarmed the devil, and ransomed his people from their sin—to name but a few of the ways Scripture speaks of Christ’s death.

In the days of crucifixion, Jesus was one of thousands who were hung on a tree. Physically speaking, his death was not remarkable, aside from the fact that his death came much quicker than most who died by crucifixion. Spiritually speaking, however, his death was unlike any other. No one else—before or since or ever—died in the place of others and rose from the grave, conferring on his people resurrection life won through his obedience unto death.

Today, there dozens of ways Christians speak of the cross—e.g., a redemption, victory, sacrifice, penal substitution, etc.—but critically two issues stand at the center of the cross. First, for whom was the cross chiefly designed? Did Jesus die to give man a moral example? Did he die to defeat the devil? Or did he die to propitiate the wrath of God? In truth, we must affirm all three realities, but only when the design of the cross is chiefly Godward do the other aspects of the cross hold together.

Second, was Christ’s death the only way of salvation or might God have forgiven man in another way? This was the question answered in Gethsemane (Matthew 26:36–46). For Jesus, the cross was the cup prepared for him to drink, and on the cross this cup—the cup of God’s wrath—he would drink to its dregs (Psalm 75:8). Truly then there was no other way.

The Nature of the Atonement

In church history debate remains around both of these assertions—that (1) Christ died chiefly for God and (2) salvation could come by no other means than the cross. But importantly, the answer to both questions come down to a vision of God himself. Is God unswervingly holy, or is some other attribute the defining feature of his character. When another attribute (typically love) takes center stage, it misconstrues the nature and necessity of the cross.

Yet, when we keep in mind God’s holiness, righteousness, and justice; when we affirm without wavering that God’s love and mercy are best seen as his holiness is preserved, then it makes it begins to reveal what Scripture says about the nature and necessity of the cross.

Yes, God is one in nature, simple in essence, and there is no one attribute that precedes the others. Yet, when we uphold the unity of God’s attributes, we cannot place his love over his justice. Rather, together they force us to consider the righteousness of the cross, the justice of Christ’s ransom, and the manner in which he defeated the devil and propitiated God’s wrath.

Jesus was not a third party (exterior to God) who accomplished salvation. As mediator between God and man (1 Timothy 2:5–6), Jesus was fully God. As God, the son of God ransomed his people from the judgment of God. And in this way, we discover the nature of the atonement—God in his love satisfied God in his holiness. The mercy of God “paid” his justice and by consequence Jesus ransomed his people from their debt to God.

The Necessity of the Cross

In this formulation, we discover something of the nature of the cross and the God-centeredness of the atonement. At the same time, such a vision of God’s holiness also shows why the cross of Christ is necessary. There is no way to avoid it; once God chose to save a people for his own glory, the cross became the only way of salvation.

While not always appreciated, this truth stands or falls with a doctrine of God. Those who understand the holiness of God know he cannot simply turn a blind eye to sin. His holy character is offended by sin and as the moral Judge and Sovereign Creator of the universe, he cannot dismiss sin without denying his own justice. Truly, this has been the doctrine understood and asserted by theologians, pastors, and laymen who keep an eye on the holiness of God.

Going back to Anselm of Canterbury, we find this understanding, that man owes God a debt for his sin. With Anselm the debt is one of honor; with Calvin and later theologians the debt is judicial. Either way, the fact remains, in Adam all humanity has sinned, fallen short of God’s glory, and stands condemned unless God himself intervenes. In his mercy and wisdom and power, God the Son took on human nature in order to pay the penalty that fallen man could never pay. And he did it as the Son of God Incarnate, because only God had the resources to pay the penalty.

First articulating this point, Anselm of Canterbury argued that God became a man in order to pay the ransom man could never pay (cf. Psalm 49:7–9). And in his classic work, Why God Became Man, we find the main point of his argument in Book 1, Article 12. Listen to his discussion with the fictitious inquisitor Boso:

12. Whether it would be proper for God to cancel sins by compassion alone, without any payment of debt.

Anselm.Would it be proper for God to cancel sins by compassion alone, without any payment of the honor taken from him?

Boso. I don’t see why not.

Anselm. How would one go about putting away sins in this way? Simply by not punishing? But it is not right to cancel sin without compensation or punishment — if it is not punished, then is it passed by and not dealt with.

Boso. That makes sense.

Anselm. But it is not fitting for God to pass over anything in his kingdom without dealing with it.

Boso. I cannot disagree without the risk of sin.

Anselm. It is therefore not proper for God to pass over sin unpunished.

Boso. That follows.

Anselm. There is also another thing which follows if sin is passed by unpunished, — that with God there will be no difference between the guilty and the not guilty. That would be inappropriate for God.

Boso. I cannot deny it . But God commands us always to forgive those who sin against us. It seems inconsistent to tell us to do something it’s not proper for him to do himself.

Anselm. It is not inconsistent for God to forbid us to do what only he should do. To take revenge belongs to none but the Lord of all….

Boso. You have solved that difficulty, but there’s another one too I’d like you to answer. God is so free that he comes under no law or judgment. He is more merciful than anything else the mind can imagine. And nothing is right unless it happens according to his will. This being the case, it seems strange to say that he is totally unwilling or unable to cancel any injury done to him — especially when we are always asking him to forgive the offences we commit against others.

Anselm. What you say of God’s liberty and choice and compassion is true; but we should not interpret these things in any way that seems to interfere with his dignity. For there is no liberty except to do what is best, we should call nothing mercy if it is at all improper for God’s character.

Moreover, when we say that whatever God wishes is just, that does not mean that if God wished anything improper it would be just, simply because he wished it. If God wishes to lie, that does not mean that it is right to lie, it means rather that he is not God. So, if it is not fitting for God to do anything unjustly, it does not belong to his liberty or compassion or will to let the sinner go unpunished if he does not return to God what he has stolen form him.

Boso. You remove from me every possible objection which I had thought of bringing against you.

Truly, when we rightly understand the holy character of God, we soon see why God cannot merely forgive sin without payment. As Romans 3:26 explains, God is “just and the justifier.” God is not just merciful in his forgiveness; he is also just (1 John 1:9). In this way, and only in this way, we learn why the cross was necessary. Only on the cross could all the attributes of God be maintained.

Truly, such a doctrine of the atonement heightens our thanksgiving and awe towards God in what he did on the cross. And more, it protects and preserves his manifold holiness. While the world would have God cater to their wishes and offer pardon at the expense of his justice; such a pitiful God who not be worthy of worship. Far better, as revealed in Scripture, is the God who lowers not his holiness for an instance, but perfectly displays his just mercy by becoming man and dying in the place of his people.

This is the God who is worthy or worship and this is the reality we remember this week as we come to Good Friday. Revisiting the cross, we recall that God is just and merciful, holy and gracious. On the cross all of the attributes of God are perfectly revealed—and not just displayed, but effectually achieving the ransom of those the Lord will save. 

This is why Good Friday is so good and why the nature and the necessity of the cross matter so much. May we ponder what the cross means and in considering the cross may we come to better know and love the God who is perfect in all his ways.

Soli Deo Gloria, ds

One thought on “The Nature and Necessity of the Cross: Why Christ Had to Die for Sin (With a Little Help from Anselm)

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