Cur Deus Homo (Why God Became Man)

In 1 Peter 3:18, the apostle gives us the heart of the gospel: “For Christ died for sins once for all, the righteous for the unrighteous, to bring you to God. He was put to death in the body but made alive by the Spirit.”

We live in a sinful world of suffering, and Christians are not exempt. They suffer because they are followers of Jesus Christ who said, “If anyone would come after me, he must deny himself and take up his cross and follow me” (Matt. 16:24). We are to follow him, though we may suffer, and even die, if needs be. In this verse, Peter is speaking about Christ’s supreme suffering and death on the cross. This is a great comfort to us when we are suffering for doing good.

In the eleventh century, St. Anselm of Canterbury wrote a book, Cur Deus Homo (Why God Became Man). It was written to answer the question of why God’s eternal Son took upon himself human nature. In other words, what is the meaning of the incarnation of the Son of God? Professor John Murray says:

He who never began to be in his specific identity as Son of God, began to be what he eternally was not. . . . The infinite became the finite, the eternal and supratemporal entered time and became subject to its conditions, the immutable became the mutable, the invisible became the visible, the Creator became the created, the sustainer of all became dependent, the Almighty infirm. All is summed up in the proposition, God became man.[1]

Why did God become man? St. Anselm’s answer is that he did so to make atonement for our sins through his substitutionary death in our place for our sins. Yes, we all will suffer in this world of sin. But Christ’s suffering was supreme. His suffering was unique. St. Augustine says that Jesus Christ was one Son without sin but not one without suffering.

The Son alone was without sin, as we read:

• 1 Peter 2:22: “He committed no sin, and no deceit was found in his mouth.”
• John 8:46: [Jesus asked,] “Can any of you prove me guilty of sin?”
• Hebrews 4:15: “For we do not have a high priest who is unable to sympathize with our weaknesses, but we have one who has been tempted in every way, just as we are—yet was without sin.”
• Hebrews 7:26: “Such a high priest meets our need—one who is holy, blameless, pure, set apart from sinners, exalted above the heavens.”
• John 18:38: “‘What is truth?’ Pilate asked. With this he went out again to the Jews and said, ‘I find no basis for a charge against him.’”
• John 1:29: “The next day John saw Jesus coming toward him and said, ‘Look, the Lamb of God, who takes away the sin of the world!’”

The sinless God/man by his death, by his atoning sacrifice, took away all our sins. The Righteous One, Jesus Christ, suffered death for the unrighteous many. Christ died his death in behalf of the sin of the elect in their place. So we read, “For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord” (Rom. 6:23). He died that we may not die.

Jesus was alone was righteous. His death involved a double transaction. Peter declared, “You disowned the Holy and Righteous One and asked that a murderer be released to you” (Acts 3:14). Paul writes, “God made him who had no sin to be sin for us, so that in him we might become the righteousness of God” (2 Cor. 5:21). So Peter says, “Christ died for sins once for all, the righteous for the unrighteous, to bring you to God. He was put to death in the body but made alive by the Spirit” (v. 18).

This is the double transaction. He took all our sin, our guilt, our penalty, our wrath, and our hell, and we are given his divine, perfect righteousness. Clothed in his righteousness, we will live forever in fellowship with our great God.

Christ died for our sins, because of our sins. He died to make atonement for our sins. He paid the price of our redemption. His death was the price. This is why God became God/man, one divine person in two natures, divine and human. The Hebrews writer says,

Since the children have flesh and blood, he too shared in their humanity so that by his death he might destroy him who holds the power of death—that is, the devil—and free those who all their lives were held in slavery by their fear of death. For surely it is not angels he helps, but Abraham’s descendants. For this reason he had to be made like his brothers in every way, in order that he might become a merciful and faithful high priest in service to God, and that he might make atonement for the sins of the people. Because he himself suffered when he was tempted, he is able to help those who are being tempted. (Heb. 2:14–18)

By Christ’s death, he destroyed our eternal death, which was the wages of sin that we both deserved and earned. His death was propitiatory. God’s wrath against us was poured out on his only Son, who cried out in anguish, “My God, my God, why hast thou forsaken me?”

God spared Abraham’s son Isaac from death but he did not spare his own Son. Isaiah says, “We all, like sheep, have gone astray, each of us has turned to his own way; and the Lord has laid on him the iniquity of us all” (Isa. 53:6). Paul writes, “He who did not spare his own Son, but gave him up for us all—how will he not also, along with him, graciously give us all things?” (Rom. 8:32). We are blessed with every spiritual blessing in heavenly places in Christ Jesus.

Now God can justify us, the ungodly elect sinners, justly, for he poured out his wrath that was against us on his own beloved Son. Paul says, “Since we have been justified through faith, we have peace with God through our Lord Jesus Christ. . . . Therefore, there is now no condemnation for those who are in Christ Jesus, because through Christ Jesus the law of the Spirit of life set me free from the law of sin and death” (Rom. 5:1, 8:1–2). We are saved by Christ, and saved forever.

Justification means that, in Jesus Christ, all the sins of those who believe in his substitutionary atoning sacrifice are forgiven forever, and that all such believers are clothed in Christ’s perfect righteousness forever. This is good news! Christ’s propitiatory sacrifice was accepted by God the Father, and the proof is Christ’s resurrection.

The resurrection also proves that Jesus was without any sin, as Peter declared in Acts 2:23–24: “This man [Jesus] was handed over to you by God’s set purpose and foreknowledge; and you, with the help of wicked men, put him to death by nailing him to the cross. But God raised him from the dead, freeing him from the agony of death, because it was impossible for death to keep its hold on him.” Death could not keep its hold on Jesus because Jesus was without sin. (PGM) Paul gives a summary of the atonement: “He was delivered over to death for our sins and was raised to life for our justification” (Rom. 4:25).

Jesus Christ was put to death in the flesh (cur Deus homo) and was raised to life by the Holy Spirit. Paul writes,

[Jesus], being in very nature God, did not consider equality with God something to be grasped, but made himself nothing, taking the very nature of a servant, being made in human likeness. And being found in appearance as a man, he humbled himself and became obedient to death—even death on a cross! Therefore God exalted him to the highest place and gave him the name that is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father. (Phil. 2:6–11)

Christ died to deal with our sins. Christ died once for all. His one-time death will not be repeated. It has achieved eternal benefit for all those who believe in Jesus. Professor Gordon Clark speaks about this in his commentary on 1 Peter 3:18:

The Roman Catholic mass is a denial of the phrase that Christ died once. The word once means just once, or once for all. When Christ died, his work was finished; he did not have to die again. The merit of his death is sufficient for all time, and nothing more need be added.

But the Roman Church teaches that the mass is a sacrifice, a repetition of Christ’s death on the cross. The sacrifice is offered by a priest, and the priest transforms the bread and wine into the actual body and blood of Jesus.

The Canons and Decrees of the Council of Trent (Twenty-second Session, September 17, 1562, Chapter II) states:

[I]n this divine sacrifice which is celebrated in the mass, that same Christ is contained and immolated. . . . [T]his sacrifice is truly propitiatory. . . . [W]wherefore, not only for the sins, punishments, satisfactions, and other necessities of the faithful who are living, but also for those who are departed in Christ and who are not as yet fully purified, is it rightly offered.

It is to be noted that the mass is said to be a propitiatory sacrifice, and is rightly offered for sin and satisfaction, or atonement. And the same Christ dies every time the mass is celebrated.

But all this is far from the teaching of Peter and the other apostles. It is an eloquent testimony to the apostasy of the Roman church that the Pope and the Councils should be able so violently to wrest the word of God to their own destruction.

The epistle to the Hebrews is particularly explicit in this regard. Not only does it speak of Christ’s sacrifice as more excellent than the Jewish rites, but it expressly contrasts the many previous sacrifices with Christ’s one sacrifice that does away with all others. “Nor yet that he should offer himself often . . . for then must he often have suffered . . . but now once. . . . So Christ was once offered . . .” (Hebrews 9:25–28).

Christ suffered for sins; and the significance of his suffering is clarified in the next phrase: the just for the unjust. In the Old Testament sin barred the way to God, and in order to worship God a man had to offer a sacrifice. An animal without spot or blemish had to die for the sinful man. Christ died as the Lamb of God, the true sacrifice of which the Old Testament sacrifices were but anticipations. Christ, without spot or blemish, Christ the just one, died for the unjust.[2]

No further sacrifice is possible. Christ died, he was buried, he was raised from the dead, he ascended into heaven, he is seated on the right hand of the Father, and he rules the universe, having received all authority from the Father. No repetition of his atoning sacrifice is possible, either in history or in symbol.

The writer to the Hebrews emphasizes three times the once-for-all nature of Christ’s one sacrifice. The infinite merit of Christ’s one sacrifice once-for-all offered is sufficient forever for the salvation of everyone he represented. So we read, “Unlike the other high priests, he does not need to offer sacrifices day after day, first for his own sins, and then for the sins of the people. He sacrificed for their sins once for all when he offered himself. . . . He did not enter by means of the blood of goats and calves; but he entered the Most Holy Place once for all by his own blood, having obtained eternal redemption. . . . And by that will, we have been made holy through the sacrifice of the body of Jesus Christ once for all” (Heb. 7:27; 9:12; 10:10). Paul also speaks of it: “For we know that since Christ was raised from the dead, he cannot die again; death no longer has mastery over him.  The death he died, he died to sin once for all; but the life he lives, he lives to God” (Rom. 6:9–10).

What is the final purpose for which the eternal Son became man? It was so that this God/man Jesus Christ, our only mediator and redeemer, may bring us to enjoy eternal fellowship with God forever. The wrath of God was against us and we were God’s enemies. But Christ, our redeemer and mediator, by his death of propitiation, satisfied God’s demands in full, so that the throne of judgment has been changed forever for believers in Jesus. It is now the throne of grace, and the Father welcomes us in Jesus into his presence.

In Christ, we now have access to the Father, as we read:

• Hebrews 4:16: “Let us then approach the throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need.”
• Romans 5:1–2: “Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ, through whom we have gained access by faith into this grace in which we now stand. And we rejoice in the hope of the glory of God.”
• Ephesians 2:18: “For through him we both have access to the Father by one Spirit.”
• Ephesians 3:12: “In him and through faith in him we may approach God with freedom and confidence.”

Now we can pray to him any time, and we can call him, “Our Father, who art in heaven.” And from our gracious heavenly Father, we receive mercy and grace every day. His mercy is new every morning. In Jesus, we are forgiven of all our sins. Now we are redeemed, justified, and adopted. Now we are clothed in God’s perfect righteousness. Now we are destined for glory.

There is no longer a curtain separating us from our holy God. When Christ died on the cross, he accomplished our redemption, and, in Matthew’s gospel we read, “At that moment the curtain of the temple was torn in two from top to bottom,” (Matt. 27:51), giving us access to God the Father. In Jesus, all God’s saints enjoy access to and fellowship with God the Father. There is no separation! Paul writes,

Who will bring any charge against those whom God has chosen? It is God who justifies. Who is he that condemns? Christ Jesus, who died—more than that, who was raised to life—is at the right hand of God and is also interceding for us. Who shall separate us from the love of Christ? . . . For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord. (Rom. 8:33–35a, 38–39)

If you are not saved by the only Savior, Jesus Christ, you must ask this question: What must I do to be saved from the eternal damnation I merit? You cannot trust in money or fame or power or anything else in this world. These things cannot save us. We must trust in Jesus Christ alone for our eternal salvation. So the answer to your question is simple and profound: Believe on the Lord Jesus Christ and you will be saved.

If you are outside of Christ, I want you to say today, “I believe in God’s Son, God/man, who in his perfect righteousness died on the cross in my place for all my sins. So by faith I died with him, was buried with him, and was raised with him to live a new life for all eternity. I am vitally united with Jesus, as branches are united with the vine.”

The life of Jesus ever flows into the branches of his people, producing the fruits of good works. Jesus said, “By their fruits, you will recognize them.” He was speaking of true believers who are known by their fruits of obedience. Fruit is living out our confession, “Jesus is Lord,” by hearing and doing his will as revealed in the holy Bible.

There is no other Savior. Jesus is the only Savior of the whole world. God called me and sent me to the end of the world to preach for these many years the good news that our Lord Jesus Christ reigns, and that his kingdom is eternal. His kingdom is righteousness, peace, and joy in the Holy Spirit to all who enter it by faith in Christ. That is my prayer for all of you. If you are outside of Christ, ask the Lord, and he will save you. And if you are already inside of Christ, let us all rejoice. Hallelujah!

[1] John Murray, Systematic Theology, Collected Writings of John Murray, vol. 2 (Edinburgh: Banner of Truth, 1977), 132.

[2] Gordon H. Clark, New Heavens, New Earth: A Commentary on First and Second Peter (Jefferson, MD: Trinity Foundation, 1993), 123–124.