How can Jesus be eternal if He had a birth?
Question 3028
This question strikes at the heart of who Jesus really is. If Jesus was born in Bethlehem around 4 BC, how can Christians claim He is eternal? Wasn’t there a point when He didn’t exist? This apparent contradiction has puzzled honest seekers and been exploited by cults for centuries. Yet the answer reveals something wonderful about the nature of our Saviour and the mystery of the Incarnation.
The Distinction Between the Son and the Human Nature
The key to understanding this lies in distinguishing between the eternal Son of God and the human nature He took upon Himself. The Second Person of the Trinity, whom we call the Son, has existed eternally with the Father and the Holy Spirit. He had no beginning and will have no end. What happened at Bethlehem was not the beginning of the Son’s existence but the beginning of His human life. The eternal Son added to Himself a human nature, being born of the Virgin Mary, without ever ceasing to be who He always was.
John’s Gospel opens with this magnificent declaration: “In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through him, and without him was not any thing made that was made” (John 1:1-3). Notice the verb tense. John does not say the Word “came into being” but that He “was” (ἦν, ēn). This imperfect tense indicates continuous existence in the past. Before anything was created, the Word already existed. And then in verse 14, John tells us that “the Word became flesh and dwelt among us.” The eternal Word took on human flesh at a point in time, but His existence stretches back into eternity past.
Old Testament Appearances of the Pre-Incarnate Son
Throughout the Old Testament, we find appearances of the Son before His birth in Bethlehem. These theophanies, often identified as “the Angel of the LORD” (מַלְאַךְ יְהוָה, malakh YHWH), reveal the Son active in history long before Mary gave birth. When the Angel of the LORD appeared to Hagar, she recognised Him as God Himself: “So she called the name of the LORD who spoke to her, ‘You are a God of seeing,’ for she said, ‘Truly here I have seen him who looks after me'” (Genesis 16:13). This was no ordinary angel but the pre-incarnate Son.
Consider also the encounter at the burning bush. The Angel of the LORD appeared to Moses, yet the text tells us “God called to him out of the bush” and identified Himself as “I AM WHO I AM” (Exodus 3:2-14). When Joshua encountered the commander of the LORD’s army near Jericho, this divine figure accepted worship and declared the ground holy, something no created angel would do (Joshua 5:13-15). In your Soteriology notes, you rightly identify that “Jehovah Elohim” often refers to the Son, since “God the Father never revealed or showed himself to anyone.” The Son has always been the One who makes God known.
Jesus’ Own Claims to Pre-Existence
Jesus Himself made clear that His existence did not begin at Bethlehem. In His great high-priestly prayer, He spoke of “the glory that I had with you before the world existed” (John 17:5). He told the Jews, “Before Abraham was, I am” (John 8:58), using the present tense ἐγὼ εἰμί (egō eimi) rather than “I was.” This echoes God’s self-revelation to Moses and claims eternal, unchanging existence. The Jews understood exactly what He meant, which is why they picked up stones to execute Him for blasphemy.
In John 6:62, Jesus asked, “Then what if you were to see the Son of Man ascending to where he was before?” He speaks of returning to a place He had previously occupied. In John 3:13, He stated that “no one has ascended into heaven except he who descended from heaven, the Son of Man.” The descent presupposes prior existence in heaven. The Incarnation was not the Son coming into existence but the Son coming into the world He had made.
The Theological Term: The Eternal Generation of the Son
Theologians have historically used the phrase “eternal generation” to describe the Son’s relationship to the Father. This does not mean the Son was created or had a beginning. Rather, it describes an eternal relationship within the Godhead. Just as the sun’s rays are not created by the sun but eternally proceed from it, so the Son eternally proceeds from the Father. The Father has always been Father, and the Son has always been Son. There was never a moment when this was not so.
The Nicene Creed (AD 325) carefully articulated this truth, declaring that the Son is “begotten of the Father before all worlds… begotten, not made.” The church fathers distinguished between being “begotten” (which refers to the eternal relationship) and being “made” (which would imply a beginning). Charles Ryrie explains that “the term ‘only begotten’ (μονογενής, monogenēs) means unique, one of a kind, and emphasises the Son’s unique relationship to the Father rather than any temporal origin.”
The Hypostatic Union
What happened at the Incarnation was the union of the eternal divine nature with a newly created human nature in one Person. This is what theologians call the hypostatic union, from the Greek ὑπόστασις (hypostasis), meaning “substance” or “person.” The Son did not cease to be God when He became man. He did not exchange divinity for humanity. Rather, He added humanity to His divinity, uniting both natures in one Person forever.
As your notes put it regarding Isaiah 9:6: “A young child is born = humanity. Son (adult mature son) = divinity.” The child born in Bethlehem is the Son given from eternity. The birth was of His human nature; His divine nature is without beginning. Lewis Sperry Chafer wrote that “the theanthropic Person, as He now exists and will exist forever, combines in Himself the divine nature which is from all eternity and a human nature which began when He was conceived in the Virgin Mary.”
Why This Matters
This truth has enormous practical significance. If Jesus were merely a created being, even the first and greatest created being, He could not save us. Only an infinite God can bear infinite wrath. Only an eternal Saviour can provide eternal salvation. As J. Dwight Pentecost observed, “The efficacy of Christ’s atoning work depends entirely upon the dignity of His Person. A finite being could not make infinite satisfaction for sin.”
Furthermore, if the Son’s existence began at Bethlehem, then there was a time when God was not Trinity. The Father would have existed without His Son. But this is impossible. The relationships within the Trinity are eternal and unchanging. God has always been Father, Son and Holy Spirit. The Incarnation changed nothing about who God is in Himself. It revealed to us what has always been true and brought the eternal Son into created time and space for our salvation.
Conclusion
Jesus can be eternal even though He had a birth because what was born was His human nature, not His divine Person. The eternal Son of God, who made all things and sustains all things, entered into His own creation by taking upon Himself a genuine human nature. He was born of the Virgin Mary so that He might redeem those who are born of Adam. He who had no beginning chose to have a birthday so that we who have no hope might have eternal life. The baby in the manger was the Ancient of Days. The child learning to walk was the One who flung the stars into space. This is the wonder of the Incarnation, and it is good news for all who believe.
“In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God.” John 1:1-2
Bibliography
- Chafer, Lewis Sperry. Systematic Theology, Vol. 1. Dallas Seminary Press, 1947.
- Ryrie, Charles C. Basic Theology. Victor Books, 1986.
- Pentecost, J. Dwight. Things Which Become Sound Doctrine. Kregel, 1965.
- Walvoord, John F. Jesus Christ Our Lord. Moody Press, 1969.
- Morris, Leon. The Gospel According to John. New International Commentary on the New Testament. Eerdmans, 1995.
- MacArthur, John. The MacArthur New Testament Commentary: John 1-11. Moody Press, 2006.
- Grudem, Wayne. Systematic Theology. Zondervan, 1994.
- Warfield, B.B. The Person and Work of Christ. P&R Publishing, 1950.
