How can Jesus be both human and God?

This is a tenfold summary of key biblical Christology.

1. The person or subject of the incarnation is the eternal, divine Son.

John 1:14 states this well: “The Word became flesh.” In other words, it was not the divine nature but the divine Son from eternity (John 1:1) who became incarnate. The Son, who has always been in eternal relationship with the Father and the Spirit, and who shares the same, identical divine nature with them, freely chose to humble himself by assuming a human nature to redeem his people (Phil. 2:6–8) and to reverse all that Adam did by ushering in a new creation (Col. 1:18–20).

2. As the divine Son, the second person of the triune Godhead, he is the exact image and correspondence of the Father and is thus truly God.

Along with the Father and Spirit, the Son fully and equally shares the one divine nature. As the image and exact correspondence of the Father (Col. 1:15; Heb. 1:3), the Son is truly God. All of God’s perfections and attributes are his since our Lord is God the Son (Col. 2:9). As the Son, he indivisibly shares the divine rule, receives divine worship, and does all divine works as the Son (Ps 110:1; Eph 1:22; Phil 2:9–11; Col. 1:15–17; Heb. 1:2–3; Rev. 5:11–12).

3. As God the Son, he has always existed in an eternally ordered relation to the Father and the Spirit, which now is gloriously revealed in the incarnation.

It was fitting that the Son alone became incarnate and not the other divine persons (John 1:1–2, 14, 18). In the incarnation, the Son revealed his eternal divine-filial relation to the Father and always acted from the Father and by the Spirit (John 5:19–30; Mark 1:12; Luke 4:1–21). These eternally ordered relations within God are eternal and necessary.

• The Father is first, has paternity due to his relation to the Son, and is the one who initiates and sends.
• The Son has filiation and is eternally generated from the Father.
• The Spirit has spiration and eternally proceeds from the Father and the Son.

In God’s acts, all three persons act inseparably through the one divine nature. Yet each person acts distinctly, with specific actions terminating on the divine persons according to their eternally ordered relations.

The result: every external act of God is one and undivided, yet the Father initiates and acts through the Son, the Son from the Father, and the Spirit from the Father and Son. Thus, from eternity and in the incarnation, the Son never acted independently but always acted about the Father and the Spirit, and he alone became incarnate.

4. The incarnation is an act of addition, not subtraction.

From eternity, the Son, about the Father and the Spirit, subsisted in the divine nature. Now, as a result of the incarnation, the Son, without change or loss of his deity, added—or, to use a better term—assumed a second nature, namely, a human nature consisting of a human body and soul (Phil. 2:6–8). As a result, the Son added a human dimension to his divine life and became present to us as the incarnate Son in a new mode of existence. 

Yet Son’s subsistence and action in both natures are consistent with the integrity, without either nature being mutually exclusive of the other. Given the incarnation, the Son can act by his two natures and produce effects proper to each nature, thus accomplishing our salvation as the divine Son who obeys us in his life and death as our covenant head and substitute.

5. The human nature assumed by the divine Son is fully human and sinless.

Christ’s human nature was unfallen and untainted by the effects of sin. Christ’s human body and soul had all the capacities of original humanity, thus enabling the Son to experience fully human life. But Christ’s humanity was unfallen and thus not tainted by the transmission or transgression of sin.

Accordingly, our inborn inclination toward rebelling against God was not part of Jesus’ human makeup. Jesus was not tempted by anything within or internal to himself. He was not enticed by sinful desires contrary to God’s creational and moral norms since there was no sin in him, not even a predisposition to sin. 

Rather, Jesus, as fully human, was tempted by normal sinless human weaknesses and external forces. He could be tempted by hunger and through fear of pain. He experienced the full effects of living in a fallen world but did not share the guilt or disposition of Adam’s sin passed on to all humanity.

Jesus never committed a sin, nor could he (Matt 3:15; John 8:46; Heb. 4:15; 7:26; 1 Pet. 1:19). Although he was tempted like us, he perfectly obeyed his Father, even unto death, as our covenant mediator, thus accomplishing our redemption as the man Christ Jesus (1 Tim. 2:5; Heb. 5:5–10). This glorious truth grounds our assurance that God’s redemptive plan cannot fail, and it explains why Jesus, as the last Adam, is far greater than the first.

6. The virgin conception was the sovereign, effectual means by which the Son assumed a human nature.

The incarnation was thoroughly supernatural, fulfilling Old Testament expectations, and a glorious demonstration of God’s sovereign and gracious initiative to redeem his people (Matt. 1:18–25; Luke 1:26–38). The virgin conception was how the divine Son added to himself or assumed a human nature. 

The act was triune: the Father sent the Son, the incarnation terminated on the Son, and the Spirit acted on Mary to sanctify her contribution and create a human nature for the Son.

As a result of this action, in Jesus, we truly meet God face-to-face, not indwelling or overshadowing human flesh but in full undiminished glory. Although we behold Jesus as a man, he is much more; he is God, the divine Son who humbles himself and veils his glory by becoming one with us.

7. From conception, the Son took on a new mode of existence as a man.

The divine Son now subsists and acts in two natures without changing the integrity of either nature, confusing them, or melding them into a divine-human hybrid. The Son’s action in his human nature is real as the Son truly lives, experiences the world, and acts as a man.

As a result of the incarnation, the divine Son lives and acts within the normal physical, mental, volitional, and psychological capacities of an unfallen, sinless human nature. As the Son, he experienced the wonder and weaknesses of human life. He grew in wisdom and physical stature (Luke 2:52), experienced tears and joy (John 11:35; 15:11), and suffered death and glorious resurrection for his people and their salvation (John 11:33, 35; 19:30; 1 Cor. 15:3–4).

8. However, in the incarnation, the divine Son was not limited to acting through his human nature alone since he continued to live and act through his divine nature, as he has from eternity.

This truth is taught in Scripture’s affirmation that the incarnate Son continues to uphold the universe (Col. 1:16–17; Heb. 1:3), even as he continues to perform other divine actions throughout his life and ministry. In Christ, two natures remain distinct and retain their own attributes and integrity, yet the Son can act through both natures.

The Son is not completely circumscribed by his human nature; he can also act “outside” (extra) his human nature in his divine nature, as he has always done. The Son, who has always acted inseparably from the Father and by the Spirit, continues to do so. Still, as a result of the incarnation, he acts as a man—indeed, as the obedient Son for us and our salvation. In the incarnation, Son’s full deity and humanity are not diminished.

9. In the incarnation, the divine Son became the first man of the new creation, perfectly qualified to be our great mediator and new covenant head.

As the Son incarnate, our Lord Jesus Christ became the first man of the new creation. As this man, he reverses the work of the first Adam. He forges ahead as the last Adam, our great trailblazer and champion (Heb. 2:10). In the incarnation, the divine Son becomes perfectly qualified to meet our every need, especially our need for the forgiveness of sin (Jer. 31:34; Heb. 7:22–28; 9:15–10:18). 

Christ alone can mediate the reconciliation of God and humans by offering himself as a sinless, sufficient, substitutionary sacrifice such that God redeems his people as a man (1 Tim. 2:5–6; Heb. 5–10). As the divine Son, Christ alone satisfies God’s judgment on sinful humanity and demands perfect obedience (Rom. 5:12–21). 

As the incarnate Son, Christ alone identifies with us as our representative and substitute (Heb. 5:1). Our salvation hope for the payment of our sin and our full restoration as God’s image bearers is accomplished only by our Lord Jesus Christ (Rom. 3:21–26; Heb. 2:5–18).

10. God the Son incarnate is utterly unique and alone, Lord and Savior, and he demand and deserves our complete faith, love, and obedience to him.

Jesus is in a category all by himself. Given who God is in all of his glory and moral perfection, and what sin is before God, apart from Son’s incarnation and his entire work for us, there is no salvation (John 14:6; Acts 4:11). For this reason, it’s not enough merely to state correctly who Jesus is. Everyone must also be led to worship, faith in him alone, proclamation, and glad and willing submission to his lordship in every area of our lives.