What Is Hypostatic Union?

Hypostatic union is how Christians explain the relationship between Jesus’ divine nature, his human nature, and his being. It means that Jesus is both fully God and fully man. Jesus has all of the characteristics that are true of a person, and all of the characteristics that are true of a divine being. Both natures fully exist in one person.

For centuries, the church struggled to define the relationship between Jesus’ divine nature and his human nature, and numerous heretical ideas emerged to try and explain it that either compromised Jesus divine nature or reduced the significance of his humanity. Hypostatic union helped the church rule out these incorrect explanations.

If you put an apple and an orange into a blender and mix them together, you can’t say that the end result is still “fully apple” and “fully orange.” It’s a new substance—a combination of the two. Jesus’ divine and human natures exist together in such a way that they are united in one person, but “unblended.” They each retain all of their qualities without interfering with the other.

Jesus got tired and needed to sit down (John 4:6). He got thirsty (John 19:28). He needed sleep (Luke 8:23). But he could also heal people and cast out demons (Matthew 8:16), forgive sins (Luke 7:48), and command nature to do his bidding (Mark 4:39).

The Council of Chalcedon

At the Council of Chalcedon in 451, the church refined its definition of hypostasis to make it more clear that Jesus’ natures remained distinct, but still united in one person. This clarification is known as the Chalcedonian Definition or Chalcedonian Creed.

Here’s how the council defined Jesus’ two natures:

“Following, then, the holy Fathers, we all unanimously teach that our Lord Jesus Christ is to us One and the same Son, the Self-same Perfect in Godhead, the Self-same Perfect in Manhood; truly God and truly Man; the Self-same of a rational soul and body; co-essential with the Father according to the Godhead, the Self-same co-essential with us according to the Manhood; like us in all things, sin apart; before the ages begotten of the Father as to the Godhead, but in the last days, the Self-same, for us and for our salvation (born) of Mary the Virgin Theotokos as to the Manhood; One and the Same Christ, Son, Lord, Only-begotten; acknowledged in Two Natures unconfusedly, unchangeably, indivisibly, inseparably; the difference of the Natures being in no way removed because of the Union, but rather the properties of each Nature being preserved, and (both) concurring into One Person and One Hypostasis; not as though He were parted or divided into Two Persons, but One and the Self-same Son and Only-begotten God, Word, Lord, Jesus Christ; even as from the beginning the prophets have taught concerning Him, and as the Lord Jesus Christ Himself hath taught us, and as the Symbol of the Fathers hath handed down to us.”

Why the hypostatic union matters

Jesus’ divine nature presents a massive stumbling block for non-Christians. How can he be God and a human? It’s also one of the greatest distinctions between Christianity and other religions: no other God became human.

Like the Trinity, the hypostatic union provides a conceptual explanation for a theological belief at the crux of the Christian faith. If we don’t understand this doctrine or how we got it, we’re left with flimsy answers to important questions--questions which become barriers to faith for some people. We may find ourselves having to shrug at crucial Christian beliefs, or worse, provide answers that drive people further away from Christ.

If we want people to accept Christ as their Lord and savior and experience the life-changing forgiveness and love he offers, we need to be able to tell them about who is offering that salvation. It’s God in the flesh.

Learn more about the Apostles Creed in Michael Bird’s online course, What Christians Ought to Believe.