What is the connection between Jesus’ birth and our new birth? What is the relationship of Jesus’ incarnation and our regeneration? The answer is: The new birth and all of its effects, including faith and justification and purification and final conformity to Christ in Heaven, would be impossible without the incarnation and life and death of Jesus—without Christmas. Let’s get a glimpse of this from 1 John.

First, consider that if there were no Jesus Christ to believe in, then the new birth would not happen. Look at 1 John 5:1: “Everyone who believes that Jesus is the Christ [that is, everyone who believes that this incarnate Jewish man from Nazareth is the promised divine Messiah] has been born of God.” 

Faith is the sign that the new birth has happened.

But that’s not the only reason the incarnation is necessary for the new birth. The incarnation of the Son of God is necessary because the life we have through the new birth is life in union with the incarnate Christ. Jesus said, “I am the living bread that came down from heaven. If anyone eats of this bread, he will live forever. And the bread that I will give for the life of the world is my flesh” (John 6:51). That life that we have in union with Christ is the life that Jesus obtained for us by the life He lived and the death He died in the flesh.

In other words, the new birth gives us life by bringing us into spiritual connection with Jesus Christ. He is our life. His new life in us, with all the changes that it brings, is the testimony of God that we are His children. And this life is the life of the incarnate Son of God. “And the Word became flesh and dwelt among us, and … from his fullness [the fullness of the incarnate one] we have all received, grace upon grace” (John 1:14, 16)—that is new birth, new life.

No Incarnation, No Regeneration

So, if there were no incarnation—no Christmas—there would be no regeneration. If there were no incarnation, there would be no incarnate Jesus Christ to believe in, and so the new birth would not happen. If there were no incarnation, there would be no vital union or connection between us and the incarnate Christ, and so the new birth would abort because there would be no source of new life.

Christianity is historically rooted in the person of Jesus Christ. Therefore, the Scripture says, “Whoever has the Son has life; whoever does not have the Son of God does not have life” (1 John 5:12). If there is no incarnation, there is no union with the Son or with the Father, and no regeneration, and no salvation.

The Incarnation and Purification

Without the incarnation of the Son of God as the Messiah, Jesus Christ, there would be no regeneration and no saving faith. And we may add then briefly, there would be no justification and no purification. And without these, no final salvation.

Purification is explicit when John says: if you have experienced the new birth, you will love the day of Christ’s appearing and long for the day when you will be transformed into his perfect likeness (as 1 John 3:2 says, “when he appears we shall be like him”). And then, John says in 1 John 3:3, “Everyone who thus hopes in him purifies himself as he is pure.” That means everyone who loves the day of his or her final purification loves purity now, and hates impurity now, and fights sin now.

This means that the new birth, which awakens faith and fills us with love for that last great day of purification, produces the fight for purity. And so, since there is no regeneration without the incarnation, there will be no purification now and no final, Christlike purity in the end, if there is no incarnation.

The Incarnation and Justification

This leaves one last great work of Christ to touch on: justification. The language of cleansing and purifying fails to deal with a huge and terrible dimension of our sin, namely, that all sin is law-breaking (see 1 John 3:4-5). We don’t just incur defilement that has to be purified, we incur guilt that has to be forgiven and wrath that has to be propitiated, and a falling short of righteousness that needs to be imputed. 

This is the work of Christ in taking away the guilt of sin, and the wrath of God that is on sin. He did it by His incarnation and life and death. Consider 1 John 4:10: “In this is love, not that we have loved God but that he loved us and sent his Son to be the propitiation for our sins.” He sent his Son—that’s the incarnation—to die in our place and so absorb the wrath of God and thus become the propitiation for our sins. The perfection we do not have, Jesus provided. The judgment we do not want, Jesus bore. ©2007 John Piper

Scriptures are taken from The Holy Bible, English Standard Version. 

This article was adapted from a sermon preached by John Piper on Dec. 23, 2007, titled “The Reason the Son of God Appeared Was to Destroy the Works of the Devil.” 

John Piper (@John Piper) is founder and teacher of DesiringGod.org and chancellor of Bethlehem College & Seminary. For 33 years, he served as pastor of Bethlehem Baptist Church, Minneapolis. He is author of more than 50 books, including Desiring God: Meditations of a Christian Hedonist and most recently Come, Lord Jesus.