What Is Hypostatic Union?

Who is Jesus Christ? One is hard-pressed to think of a more important question. Many have tried to fit Jesus into their particular worldview, and in doing so have tragically misunderstood who He is. There has therefore been a plethora of false teaching about Jesus since He walked the earth, even among professing Christians.

In contrast, orthodox Christians have carefully summarized the Bible’s teaching on the person of Christ in the doctrine of the hypostatic union. There are three key elements in this doctrine.

The Full Deity of Christ

The first is the full deity of Christ. The Bible insists that Jesus Christ is fully God. He is explicitly called “God” in several places (e.g., John 1:1, 18; 20:28; Titus 2:13; Heb. 1:8). He has divine attributes, such as omniscience (John 16:20; 21:17), omnipotence (Matt. 8:26–27; cf. Ps. 107:28–29), omnipresence (Matt. 18:20; 28:20; Rom. 8:10), and eternity (John 1:1; 8:58).

Divine titles are ascribed to Him (e.g., “Son of God,” John 5:18; “I Am,” John 8:58; “Alpha and Omega,” Rev. 22:13). He performs divine acts, such as creating (John 1:3), sustaining all things (Col. 1:17), forgiving sins (Mark 2:1–12; Acts 5:31), granting salvation and eternal life (John 3:16; Acts 4:12; Rom. 10:12–17), raising the dead (John 5:21; 6:40; 11:1–44), and exercising final judgment (John 5:19–29; Acts 10:42). He is identified with Yahweh in the Old Testament (cf. John 12:40–41 with Isa. 6:1–10). He receives from human beings what is appropriate for only God to receive, such as worship (Matt. 14:33; 28:9, 17; Heb. 1:6; Rev. 5:8–12), prayer (Acts 7:59–60; 9:1–17; 1 Cor. 1:2), and trust for salvation (Acts 10:42–43; 16:31; Rom. 10:8–13). It is no exaggeration to say that if Jesus is not fully divine, then the Christian faith is blasphemous.

The Full Humanity of Christ

The second key element of the hypostatic union is the full humanity of Christ. While affirming His deity, the Bible insists on His full humanity at the very same time. He Himself acknowledged His own humanity (Matt. 4:3–4; John 8:40) as did those who knew Him (Acts 2:22; Mark 6:1–6). The New Testament writers affirm His humanity (1 Tim. 2:5; John 1:14; Gal. 4:4; 1 Cor. 15:21), and John warns of the seriousness of denying it (1 John 4:2–3).

“There has therefore been a plethora of false teaching about Jesus since He walked the earth, even among professing Christians.”

He was born like us (Luke 2:7), grew up like us (Luke 2:40, 47), ate, drank, and slept like us (Matt. 8:23–24; 4:2; John 4:6; 19:28), experienced the whole range of emotions like us (Matt. 26:38; 8:10; 9:36; John 11:35; 12:27; Mark 3:5), was tempted like us (Matt. 4:1–11; Heb. 4:15), and even physically died like us (Luke 23). Without Jesus’ full humanity, He could not be our faithful high priest who dealt with our sin on our behalf (Heb. 2:14–18), nor could He be the true Son of David and thus our messianic deliverer in fulfillment of prophecy (Rom. 1:2–3; cf. Matt. 1 and Luke 3), nor could He be the second Adam, the paradigm for redeemed humanity (1 Cor. 15:45–49; Rom. 5:12–21).

The Unity in Christ

The third key element of the hypostatic union is the reality that Jesus’ divine and human natures are united in His one person. The Greek word hypostasis was the term used in the early church for the person of Christ—hence “hypostatic union.” Because Scripture always presents Christ as one person, those two natures are genuinely united in His one person; He is not divided into two people, a divine Jesus and a human Jesus. Yet, because Scripture upholds the integrity of those two natures as complete, they are not mixed together into some hybrid nature, neither fully human nor fully divine.

In sum, the doctrine of the hypostatic union maintains that, as a result of His incarnation, Jesus Christ has both a fully divine and a fully human nature, which are forever united in His one person without any mixture, change, or separation. This biblical doctrine was formally affirmed in the Chalcedonian Creed of 451, a creed embraced by all orthodox Christians up to the present day. The creed sought to address the challenges of various Christological heresies (false teachings about the person of Christ) that had arisen up to that point.

Hypostatic Heresies

What are some of those heresies? Several of them opposed the true deity of Christ. For example, the Ebionites were an early Jewish-Christian sect that viewed Jesus only as a human Messiah endowed with special divine power. Far more significant was Arianism, which claimed that Christ was the first and greatest created being who, though God-like, was not truly God. Other heresies have rejected Christ’s true humanity. For example, docetism believed that human flesh was inherently evil and thus incompatible with Christ’s deity. They therefore denied that Christ was human at all, insisting that He only seemed to be human (the name comes from the Greek dokeo-, “to seem or appear”).

More subtly, Apollinarianism denied Christ’s full humanity as it asserted that the divine Christ took on a human body but not a human spirit. And then some heresies denied the unity of these two complete natures in Christ’s one person. Nestorianism, for instance, so downplayed the union of the two complete natures that it ended up treating Jesus like two people (one human, one divine). At the opposite end of the spectrum, monophysitism (or Eutychianism, named after a prominent advocate) so stressed the union of the two natures that it effectively merged the two natures into one divinely-dominated nature.

Why Does This Matter?

While the careful formulation of the doctrine of the hypostatic union is noteworthy, how much does it really matter after all? Isn’t it enough just to believe in and love Jesus? That’s crucial, to be sure, but one must in fact believe in and love the real Jesus. John affirms that one who gets the person of Christ wrong— whether in His deity or humanity—actually opposes Him and is excluded from a relationship with God (1 John 2:22–23; 4:2–3; 5:5). There are very good reasons for this, some of which we saw earlier. But consider two more.

First, Christ is the mediator between God and humans (1 Tim. 2:5). In our union with Him in His full humanity, He brings us to God; in His identity as truly divine, He brings God to us; and in the unity of both natures in His person, He fully reconciles us to God.

Second, Christ is the sufficient sacrifice for our sins, but only as fully human can He take the place of human beings, and only as God can He fully satisfy the penalty for humanity’s sins. This sufficient sacrifice depends not only on the hypostatic union but also on His sinless life, a doctrine to which we now turn.