Merry Christology or Happy Heresy? The Hypostatic Union

Continuing our Christmas/Incarnation series on Christological heresies, we come to what is perhaps the most complicated of these issues: the Hypostatic union. Many ancient heresies were rejected for what they believed about how the human and the divine met on Christmas night 2,000 years ago. Was Jesus a demi-god, part man, part God? Was Jesus more human than God? Was Jesus all God, no human? Many heresies accept the wrong answer to those questions, but the heresy in view today is known as Monophystism or Eutychianism.

The Hypostatic Union

To understand the Hypostatic Union, it may help to begin with what the doctrine is not. An analogy which may assist you is thinking of pouring water into a cup. This is how many minds are prone to interpret the Incarnation. A human body was filled with a divine Person. However, Jesus was not just a human body filled with one divine nature. Jesus took on more than a human body, he took on “flesh,” and that word represents not just a body, but an actual human nature.

Paul says in 1 Corinthians 15 that “flesh and blood cannot inherit the kingdom” (50) immediately before telling us that physical bodies will inherit the kingdom,

“For this perishable body must put on the imperishable, and this mortal body must put on immortality (53).”

For Paul, flesh and blood is more than just a bag of meat and bones. It describes humanity. When Jesus took on flesh, he did not zip up a man suit over His divine nature, he took on a human nature.

This is why the Hypostatic Union has been able to maintain, without contradiction, that Jesus is fully God and fully man. A person with only one nature certainly could not claim that. However, a Person with two natures can. Jesus was fully God, but was also fully man.

The Bible is clear on this throughout the New Testament pages when ascribing things to Jesus that cannot be ascribed to a God without a human nature. Jesus partook of the full range of human experience. He got tired (Mark 4:38), He wept (John 11:35), He learned (Luke 2:52), He was tempted (Mark 4), He got frustrated and angry (Matthew 21:12), and He even lacked knowledge (Matthew 24:36). On top of all that, He was born from a woman, nursed as an infant, and able to die on a cross. If Jesus had a human body, but lacked a human nature, these things would not make sense. They would be reason to reject the divinity of Christ.

Perhaps no other place in Scripture is better to turn to on this topic than the book of Hebrews. Hebrews seeks to explain Christ’s role as Mediator on behalf of His people, and the Incarnation is essential to that office.

Since therefore the children share in flesh and blood, he himself likewise partook of the same things, that through death he might destroy the one who has the power of death, that is, the devil, 15 and deliver all those who through fear of death were subject to lifelong slavery. 16 For surely it is not angels that he helps, but he helps the offspring of Abraham. 17 Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people. 18 For because he himself has suffered when tempted, he is able to help those who are being tempted (Hebrews 2:14-18).

Jesus had to be made like humans in every respect. A god dressed up as a human is not like us. That god still cannot empathize with humanity. That god does not know what it means to be human. Jesus is a God who was made like us in every respect but sin. He did more than take on a shell, He took on a nature. He took on a sinless human nature, and became fully, and truly man. This is why He can stand on your behalf before the Father. He was truly like you; He was not playing dress up.


Monophystism (also known as Eutychianism) was a 5th century heresy that maintained Jesus had only one nature, that the divine and the human mixed together to create one nature. However, this makes Jesus a demi-God. This makes Him not truly man, but partially man. This is a Jesus who cannot intercede for us men, since He never knew our true experience.

Any belief that mixes Jesus’ natures, or denies the full status of one, is heresy. Jesus was not just a man, but God. Jesus was not just God, but man. Jesus was not a demi-God. Outside of the Hypostatic Union, those are your only three options. The man, the God, the demi-God, or the God-man.

And only one of those can save you…


Our minds tend to drift to what is most simple, to what is easiest to understand. Believing that Jesus was a Person with only one nature, merely wrapped in a human carcass, is much easier to understand than a two-natured Person. After all, people only have one nature, how then can Jesus have two? When I pour two liquids into a cup, they mix. How do Jesus’ natures remain distinct? Certainly it is one of the greatest divine accomplishments in all of human history. Certainly nothing in all the earth is like it!

However, Scripture, not simplicity, is our standard of truth. Scripture is our rule of faith. And the same Scriptures that recognize Jesus as fully God recognize Him as fully human. 

And if our minds would drift more to the beautiful, rather than to the simple, this heresy would not be such a temptation for us. For Monophystism is significantly less beautiful than the Hypostatic Union. The Hypostatic Union is a beautiful truth wherein God actually became a human. He didn’t just look like one of us; He was one of us. He breathed our air, He walked our sod, He bled our blood, He died our death, He felt our emotions. He utterly knows how difficult human life can be. And all of that was so He could save us, and always stand on our behalf before the Father.

Hebrews 4:14-16,

Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession. 15 For we do not have a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sin. 16 Let us then with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need.

Many churches affirm this beautiful truth in the songs they sing. My favorite is found in the first stanza of the song which came to be known as Before the Throne of God Above, first titled, The Advocate.

Before the throne of God above 
I have a strong and perfect plea, 
a great High Priest Whose name is love, 
Who ever lives and pleads for me. 
My name is graven on His hands; 
My name is written on His heart. 
I know that while in heaven He stands 
no tongue can bid me thence depart.

The Creed of Chalcedon 

The Monophystism heresy was condemned by the Chalcedonian council with this creed:

We, then, following the holy Fathers, all with one consent, teach people to confess one and the same Son, our Lord Jesus Christ, the same perfect in Godhead and also perfect in manhood; truly God and truly man, of a reasonable soul and body; consubstantial with the Father according to the Godhead, and consubstantial with us according to the Manhood; in all things like unto us, without sin; begotten before all ages of the Father according to the Godhead, and in these latter days, for us and for our salvation, born of the Virgin Mary, the Mother of God, according to the Manhood; one and the same Christ, Son, Lord, only begotten, to be acknowledged in two natures, inconfusedly, unchangeably, indivisibly, inseparably; the distinction of natures being by no means taken away by the union, but rather the property of each nature being preserved, and concurring in one Person and one Subsistence, not parted or divided into two persons, but one and the same Son, and only begotten, God the Word, the Lord Jesus Christ; as the prophets from the beginning [have declared] concerning Him, and the Lord Jesus Christ Himself has taught us, and the Creed of the holy Fathers has handed down to us.

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