The Necessity of the Two Natures in Christ

Many do not recognize the necessity of assuming two natures in Christ. To them Jesus is but a man; yet at the same time they feel constrained to ascribe to Him the value of a God, or to claim divinity for Him in virtue of the immanence of God in Him, or of the indwelling Spirit. The necessity of the two natures in Christ follows from what is essential to the Scriptural doctrine of the atonement.

The necessity of His manhood.

Since man sinned, it was necessary that the penalty should be borne by man. Moreover, the paying of the penalty involved suffering of body and soul, such as only man is capable of bearing, John 12:27; Acts 3:18; Hebrews 2:14; 9:22. It was necessary that Christ should assume human nature, not only with all its essential properties, but also with all the infirmities to which it is liable after the fall, and should thus descend to the depths of degradation to which man had fallen, Hebrews 2:17, 18. At the same time, He had to be a sinless man, for a man who was himself a sinner and who had forfeited his own life, certainly could not atone for others, Hebrews 7:26. Only such a truly human Mediator, who had experimental knowledge of the woes of mankind and rose superior to all temptations, could enter sympathetically into all the experiences, the trials, and the temptations of man, Hebrews 2:17, 18; 4:15-5:2, and be a perfect human example for His followers, Matthew 11:29; Mark 10:39; John 13:13-15; Philippians 2:5-8; Hebrews 12:2-4; 1 Peter 2:21.

The necessity of His Godhead.

In the divine plan of salvation it was absolutely essential that the Mediator should also be very God. This was necessary, in order that (1) He might bring a sacrifice of infinite value and render perfect obedience to the law of God; (2) He might bear the wrath of God redemptively, that is, so as to free others from the curse of the law; and (3) He might be able to apply the fruits of His accomplished work to those who accepted Him by faith. Man with his bankrupt life can neither pay the penalty of sin, nor render perfect obedience to God. He can bear the wrath of God and, except for the redeeming grace of God, will have to bear it eternally, but he cannot bear it so as to open a way of escape, Psalm 49:7-10; 130:3.

Adapted from Louis Berkhof's Systematic Theology