How can Jesus Christ be fully God and fully man at the same time? Scripture does not ask us to choose one truth and weaken the other. It shows us the eternal Son truly becoming man without ever ceasing to be God.
One Person With Two Complete Natures
The phrase hypostatic union is a doctrinal name for what the Bible reveals about Jesus Christ. He is one Person with two complete natures: truly God and truly man. He is not half of each. Nor did a human being later become divine. The eternal Son truly became man; He did not put on humanity as a disguise.
The Greek background can help if we keep it simple. In doctrinal use, hypostasis points to a person or personal existence. The word physis means nature. “Person” answers who Jesus is: the eternal Son. “Nature” answers what He is: fully divine and fully human.
I think this distinction is important because it keeps us from dividing Christ into two persons, as though a divine person and a human person were cooperating side by side. It also keeps us from blending deity and humanity into a third kind of nature that is neither fully God nor fully man. The eternal Son took a complete human nature to Himself, but the Person remained one.
Older Christian language says that the two natures are united “without confusion or change” and “without division or separation.” Those phrases protect different parts of Scripture’s testimony. The divine nature did not become human, and the human nature did not become divine. The Son never lost or reduced His deity. Nor should we speak of the union as though it divided Jesus Christ into two persons.
I find it helpful to keep returning to that basic difference between person and nature. The same Person who was born of Mary is the eternal Word. At times Scripture speaks about what He experienced in His true humanity, while other passages show what belongs to His deity. Both are true of the one Lord Jesus Christ.
This distinction may sound technical, but it is closely connected to salvation. If Jesus were not truly God, He could not reveal the Father perfectly or forgive sins by His own authority. The worship He receives would be wrong, and His victory over death could not give us complete salvation. A created being cannot carry the identity and work Scripture gives to the Son.
If Jesus were not truly man, He could not stand as our kinsman Redeemer or obey God in our nature. His suffering, blood, death, and bodily resurrection would not belong to real human history. The gospel requires the same Jesus to be fully divine and fully human, because only the God-Man can bring God and humanity together.
The Word Became Flesh
In the beginning was the Word, and the Word was with God, and the Word was God.
John begins before Bethlehem. The Word already was in the beginning. He was “with God,” which shows personal distinction, and He “was God,” which states His full deity. The Son is not the first creature or the highest created being. He is eternal, personal, and divine, and all things were made through Him.
John then tells us that the Word became flesh. He did not stop being what He eternally was. He became what He had not been before by taking true humanity to Himself. The incarnation is addition, not subtraction. The Son did not lay aside deity in order to become man.
And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth.
“Flesh” does not mean sinful nature in this verse. It means that the Son entered real human life. He took a body, lived under the law, grew from infancy to adulthood, and walked among sinners without sharing their sin. He did not merely appear human or remain untouched by ordinary human weakness.
The virgin birth shows that this humanity was holy from the beginning. Jesus was not conceived by Joseph or any earthly father. Matthew says that Mary was found with child of the Holy Spirit before she and Joseph came together. Gabriel told Mary that the Holy Spirit would come upon her and that the power of the Highest would overshadow her.
The virgin conception does not make Christ’s humanity less real. Jesus truly received human nature from Mary and was truly born from her. At the same time, His conception was the work of the Holy Spirit. The Son did not begin to exist in Mary’s womb. The eternal Son was entering the human life He had chosen to take.
“Behold, the virgin shall be with child, and bear a Son, and they shall call His name Immanuel,” which is translated, “God with us.”
Luke 1:35 calls the child “that Holy One” and says He will be called the Son of God. Jesus was holy from conception. He did not inherit Adam’s guilt and corruption as ordinary descendants of Adam do. He is the Lamb without blemish and without spot.
Matthew explains Immanuel as “God with us.” The name does not mean that the child is only a symbol of divine nearness. The One born of the virgin is God Himself dwelling among His people in true humanity. The child Mary carried was the eternal Son, not a new human person later joined to God.
His Humanity Was Real and Complete
And Jesus increased in wisdom and stature, and in favor with God and men.
Luke does not present the childhood of Jesus as theater. The Son truly lived a human life. After His conception and birth, He was nursed and carried as a child, then grew up in a household where He was cared for and taught. At twelve years old He sat among the teachers in the temple, listening to them and asking questions, while those who heard Him were amazed at His understanding.
Luke says that Jesus increased in wisdom and stature. We need to receive that statement with reverence rather than explaining it away. According to His divine nature, the Son is eternally perfect and knows all things. According to His human nature, He had a real human mind and passed through true human development. His deity did not become ignorant, but His humanity was not an illusion.
This is one reason it is wrong to say that Jesus had a human body without a human mind or soul. He took complete humanity. His human life included thought and reason. He loved and obeyed, and Scripture says He was troubled in soul. If He took only part of our nature, He would not truly share the human life He came to redeem.
The Gospels make His humanity unmistakable. Jesus became hungry after fasting in the wilderness. When He grew weary, He sat beside Jacob’s well. He slept in the boat during a storm, and He wept at the tomb of Lazarus. His suffering also took place in a real body. His blood was shed, and He truly died and was buried. None of these events was an appearance staged by someone who only seemed human.
For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin.
His temptations were real, and His sinlessness was complete. Satan tempted Him in the wilderness, but Jesus answered with Scripture and obeyed the Father perfectly. He knew hunger and sorrow. He experienced rejection, pain, and suffering, yet no sinful desire ever ruled Him and no sinful action ever came from Him.
This real humanity allows Him to sympathize with our weaknesses as High Priest. Sympathy does not mean that Jesus had to sin in order to understand us. Sin is not what makes someone fully human. Christ shows perfect humanity precisely because He endured temptation and suffering without rebellion against God.
Every teaching that makes His humanity only apparent empties these passages of their force. His hunger was not a display, His tears were not pretend, and His death was not an illusion. The same is true of His human mind and soul. Christ did not take a body as a shell while deity replaced the inner life of a man. He lived a whole and sinless human life.
His Deity Was Full and Unreduced
For in Him dwells all the fullness of the Godhead bodily.
The incarnation did not make the Son less than God. Paul says that all the fullness of the Godhead dwells in Christ bodily. That leaves no room to reduce Jesus to an exalted creature, a temporary appearance of God, or a partly divine being. His deity remained complete when He took humanity.
Jesus spoke and acted with divine authority. The crowds recognized that He did not teach like the scribes. He forgave sins, and His opponents understood the claim behind those words when they asked who could forgive sins but God alone. Jesus then healed the paralyzed man so they would know that the Son of Man had authority on earth to forgive sins.
His knowledge and works also reveal who He is. Jesus saw Nathanael before Philip called him and knew what was in people. He exposed the thoughts of His opponents and told the Samaritan woman the truth about her life. He commanded the wind and sea, while sickness, demons, and even death obeyed Him. These works did not turn Jesus into God; they revealed the divine identity He already possessed.
Jesus said to them, “Most assuredly, I say to you, before Abraham was, I AM.”
Jesus did not merely say that He existed before Abraham. He said, “I AM.” The leaders understood the force of the claim, which is why they took up stones. His deity does not rest on this verse alone. Scripture’s united witness includes His divine names, works, worship, authority, eternality, and bodily resurrection.
The man who slept from weariness in the boat was the Lord who commanded the wind and sea. The One who thirsted beside the well offered living water. Jesus wept at Lazarus’s tomb and then called the dead man out. The Lord of glory was truly nailed to the cross. These are not two Christs taking turns. They are acts and experiences of the one incarnate Son.
Nor should we imagine that His two natures blended whenever He acted. The divine nature remained divine, and the human nature remained human. The Person acting was always the one Son. That is why Scripture can speak of the Lord of glory being crucified without teaching that the divine nature ceased to be immortal or that God stopped being God.
Knowledge and Submission in the Servant Mission
Some passages emphasize Christ’s divine knowledge, while others show human development or submission to the Father. We should not protect one group by denying the other. The hypostatic union helps us receive the whole witness of Scripture: one Person acts according to two complete natures.
“But of that day and hour no one knows, not even the angels in heaven, nor the Son, but only the Father.”
When I read Mark 13:32 beside the rest of these passages, I do not believe it denies the deity of Jesus. The same Lord says that He and the Father are one. He receives worship and forgives sins by His own authority. He knows what is in human hearts, and He declares His existence before Abraham. His statement about the day and hour must be read within the incarnation and His mission as the obedient Servant.
The Son did not stop being omniscient in His divine nature. At the same time, He truly lived a human life in obedient submission to the Father. In that servant mission He did not disclose the day or act independently from the Father’s appointed will. We should not turn that submission into a denial of His eternal deity.
Philippians 2 requires the same care. When Paul says Christ made Himself of no reputation and took the form of a bondservant, he is not teaching that the Son emptied Himself of deity. The passage explains His humility through what He took and how He obeyed. He came in the likeness of men, took the servant’s form, and humbled Himself to the point of death. He did not become less than God.
Within the Trinity there is perfect unity of divine essence and a real order in role. The Father is God, the Son is God, and the Holy Spirit is God. The Father sent the Son, the Son obeyed the Father in the work of redemption, and the Spirit bears witness to the Son. This harmony does not divide the one God or make the Son inferior in divine nature. Submission in mission is not inferiority of essence.
John 10:30 keeps that equality before us: “I and My Father are one.” Philippians 2:6-8 keeps the servant mission before us. We need both passages. Christ’s willing obedience shows the unity of the Father and Son in redemption rather than conflict between them.
A lower view of Christ cannot solve these passages. Calling Him a created being contradicts the Word who was God in the beginning and through whom all things were made. Dividing Him into two personal subjects cannot account for the fact that the same Jesus is both Mary’s son and the eternal Word. Blending the natures creates a being Scripture never describes. The biblical confession keeps His full deity, complete humanity, and one undivided Person together.
Only the God-Man Can Be the Mediator
For there is one God and one Mediator between God and men, the Man Christ Jesus.
The hypostatic union is essential to Christ’s work as Mediator. Jesus is not an outsider to God, because He is God the Son. He is not an outsider to humanity, because He truly became man. He alone can stand between God and human beings because He fully represents both in His one Person.
Hebrews 2 says that the children shared in flesh and blood, and the Son likewise took part in the same. He became man so that He could truly die. Through that death He broke the devil’s power and released those who had been held by the fear of death. A divine nature cannot die, but the divine Person of the Son truly died according to the human nature He had taken.
By sharing flesh and blood, Jesus came near as the merciful and faithful High Priest Hebrews describes. He did not rescue humanity from a distance. He entered the condition of those He came to save while remaining without sin. He can therefore represent His people before God and give help to those who are tempted.
Christ had to be truly man in order to suffer and die in our nature. He had to be sinless for His death to be an acceptable sacrifice. He had to be God for His saving work to possess infinite sufficiency and divine authority. No mere prophet, created angel, or exalted martyr could accomplish what the incarnate Son accomplished.
Jesus physically bore the punishment for our sins in His innocent body on the cross. He endured real torture and shed real human blood. He died and was buried, then rose bodily from the dead. Because He is truly man, His suffering and blood were real. Because He is truly God, this was the saving work of the Lord of glory rather than the death of a mere martyr.
And without controversy great is the mystery of godliness: God was manifested in the flesh, justified in the Spirit, seen by angels, preached among the Gentiles, believed on in the world, received up in glory.
The mystery of godliness is not that an inspiring religious teacher appeared. God was manifested in the flesh. Nor did the resurrection and ascension undo the incarnation. The risen Jesus remains the incarnate Son, now glorified in real humanity, and He intercedes for believers as their living High Priest.
His bodily resurrection shows that Jesus did not discard the humanity He had taken. The tomb was empty, and the risen Lord could be seen and touched. His human body was glorified, not abandoned. The One at the Father’s right hand remains both God and man, which means His priestly work continues in the same Person who died and rose for us.
This is why the doctrine leads naturally to worship. We do not worship a created being, a divided Christ, or someone who only appeared human. We worship Jesus Christ, the eternal Son made flesh. He is our Lord and Savior, the one High Priest who sympathizes with our weaknesses and is able to save completely those who come to God through Him.
For related studies, see A Complete Bible Study on The Deity of Jesus, A Complete Bible Study on The Virgin Birth, and A Complete Bible Study on the Trinity.
My Final Thoughts
When I follow these passages together, I do not see an abstract doctrine meant only for theologians. I see the truth of who Jesus is: the eternal Son who came near without giving up His deity and who entered our humanity without sharing our sin. Because He is truly man, He can sympathize with our weakness and represent us before God. Because He is truly God, His saving work has divine authority and complete sufficiency. The hypostatic union gives us confidence to come to Christ in worship and for mercy, knowing that our living High Priest is both God with us and the Man Christ Jesus.