Introduction

The doctrine of the hypostatic union is vast and rich and is something that is crucial for our salvation in Christ. The Heidelberg Catechism instructs us this way regarding his humanity:

Q 16. Why must he be very man, and also perfectly righteous?

A. Because the justice of God requires that the same human nature which has sinned, should likewise make satisfaction for sin; and one, who is himself a sinner, cannot satisfy for others.

And again, it instructs us this way regarding his divinity:

Q 17. Why must he in one person be also very God?

A. That he might, by the power of his Godhead sustain in his human nature, the burden of God’s wrath; and might obtain for, and restore to us, righteousness and life.

The Westminster Confession of Faith is also helpful, saying:

"The Son of God, the second person of the Trinity, being very and eternal God, of one substance and equal with the Father, did, when the fullness of time was come, took upon Him man’s nature, with all the essential properties, and common infirmities thereof, yet without sin; being conceived by the power of the Holy Ghost, in the womb of the virgin Mary, of her substance. So that two whole, perfect, and distinct natures, the Godhead and the manhood, were inseparably joined together in one person, without conversion, composition, or confusion. Which person is very God, and very man, yet one Christ, the only Mediator between God and man." WCF 8.2

And finally, and most importantly, the scriptures urge us to know and believe in Christ truly, saying:

"...unless you believe that I am he you will die in your sins.” - John 8:24

Jesus Christ: Divine

Jesus Christ is deity. He is God and Lord, He is Yahweh (Jude 5), and there is no way in which he falls short - in any sense - of the fullness of any of these titles. Considering the biblical teaching regarding the divinity of Christ. One place to look would be to the teaching of Paul found in Philippians 2. In verse 6 Paul plainly traces Christ’s life from eternity past, when he was in the form of God and equal to God, saying, “though [Jesus] was in the form of God, [he] did not count equality with God a thing to be grasped.” This is a clear attestation from Paul to the absolute divinity of Christ. Again in Colossians 1:15-16 Paul speaks of the preeminence of Christ asserting that Jesus is the image of the invisible God and that by him all things have come into being. And without the power of being within himself – which is a characteristic that only God possesses – this statement could not be considered true. And again, in Colossians 2:9 Paul states that “in [Jesus] all the fullness of Deity dwells in bodily form.” These are but a few excerpts from the New Testament extolling the absolute nature of the divinity of Christ, but even with these only there is absolutely zero ambiguity in the New Testament regarding the true nature of Jesus Christ.

Jesus Christ: Human

The humanity of Christ is also on full display in the New Testament. In Galatians 4 Paul teaches us that God the Father sent his eternal Son, Jesus Christ, to be born of a woman, and to be born subordinate to the law of God. Humans are born of women as we know from experience, but also 1 Corinthians 11:12 tells us that it is man who is born of women, helping us understand that Jesus was not some glowing baby gestating in Mary’s womb. he was a real baby just like you and I were. Jesus got hungry (Matthew 4:2), he wept (John 11:35), and he got tired (Matthew 8:24) among other things indicating his humanity.

But the bible doesn’t hesitate to place Jesus’ divinity and humanity right alongside each other, because although he was born of a woman under the law, this happened so that the eternal Son of God could redeem all those born under the law, so that we might receive the adoption as sons (Galatians 4:4-5). Christ also became subject to temptation in his incarnation (Matthew 4:1) allowing him to symathize with all the temptations we encounter. Hebrews 4:15 tells us that Jesus sympathizes with our weaknesses not just because he knows of them cognitively, but because he experienced these temptations firsthand, and yet overcame them as he relied on the strength from the Father.  

Conclusion

The dual nature of Christ is vital to our salvation because without Christ being truly God he would not have been able to bear the penalty of the sins of mankind. Acts 4:12 and Isaiah 43:11 both proclaim that there is salvation in none other than God, and that God is Jesus Christ. Also, it is precisely because Jesus is truly God he is a suitable mediator between man and God (1 Timothy 2:5). Likewise, in his humanity he reveals God to us by his compassion and mercy, but also by his humanity he becomes our elder brother and can sympathize with our weakness giving us comfort and encouragement in our times of trial and need (Hebrews 2:17, 4:15). Unless Christ became man, sins could not have been forgiven because we would not have had someone to represent us for righteousness sake, as Adam represented us for unrighteousness (Roman 5:19).