In the garden, Adam and Eve needed neither redeemer nor mediator. They were free to bathe in the presence of God and to enjoy the world that He given them to steward. But they rejected their communion with God in a feeble attempt to seize even more power than God had already granted them. Although they were made in God’s image and likeness, they wanted to become gods themselves. Their rebellion opened a chasm between them and their Creator, in Whom is not even the slightest hint of sin. As a symbol of this separation, our parents were exiled from Eden, cast away from God’s presence. Whenever we sin, we follow the well-trodden footsteps of our ancestors, keeping the path clear for our descendants to follow after us. That the story of all humanity. We sin against God, and the chasm stands between us and Him.

By the great mercy and steadfast love of God, He has made a way for us to be redeemed of our sins and brought back into His favor. That singular way to restored communion with God is only through the Lord Jesus Christ. 1 Timothy 2:5 declares this: “For there is one God, and there is one mediator between God and men, the man Christ Jesus.” As does John 14:6, where Jesus said, “I am the way, and the truth, and the life. No one comes to the Father except through me.”

Our present question displays why Jesus alone is able to be our redeemer and mediator. Only one who is truly human and also truly God is able to bridge the chasm between the everlasting Holy One and sinful men.

This doctrine of Christ’s perfect humanity and divinity, called the hypostatic union, stands beside the Trinity as one of the great mysteries of Christianity. Jesus is one person, yet He bears two natures, that of both God and man. He is truly human and truly God. He is not a glorified man who looks somewhat divine, as Arians believe. Neither is He God who only appeared to resemble a man for a time, Docetism teaches. He is not a demigod, who is partially divine and partially human, nor is He sometimes God and sometimes man.

Regarding this great doctrine, there is perhaps no better concise description than the one given in the Definition of Chalcedon, which is worth quoting in full:

Following the saintly fathers, we all with one voice teach the confession of one and the same Son, our Lord Jesus Christ: the same perfect in divinity and perfect in humanity, the same truly God and truly man, of a rational soul and a body; consubstantial with the Father as regards his divinity, and the same consubstantial with us as regards his humanity; like us in all respects except for sin; begotten before the ages from the Father regards his divinity, and in the last days the same for us and for salvation from Mary, the virgin God-bearer, as regards his humanity; one and the same Christ, Son, Lord, only-begotten, acknowledged in two natures which undergo no confusion, no change, no division, no separation; at no point was the difference between the natures taken away through the union, but rather properties of both natures is preserved and comes together into a single person and a single subsistent being; he is not parted or divided into two persons, but is one and the same only-begotten Son, God, Word, Lord Jesus Christ, just as the prophets taught from the beginning about him, and as the Lord Jesus Christ himself instructed us, and as the creed of the fathers handed it down to us.

Without Jesus being truly human and truly God, He could not be our Redeemer. As a man, Jesus was able truly human as we were designed to be. He became like us in every way except for sin, which is to say that He became as we were meant to be. He became the second Adam, yet He resisted the pull of sin that the first Adam fell into. When offered the fruit from Eve, Adam ought to have rejected the temptation, slew the serpent, and then offered himself to die in Eve’s place. As the second Adam, that is precisely what Jesus did for us, His Bride.

Yet Jesus’ death would have been insufficient unless He was also God. How can one man’s physical death cover the eternal spiritual death that was the consequence of sin? Only the infinite One Himself could pay our infinite debt against Him. Since God was sinned against, only God could also redeem.

Without both Jesus’ divinity and humanity, He could not be our mediator. Yet He, the God-man, is. He is the way that has been made across the divide, and there is no other. How could there be? To claim another path to God makes a mockery of the cross. Further, it makes a mockery of God humbling Himself to become a man. Jesus has not left other options open. We must either accept Him or reject Him, but we cannot view Him half-heartedly as one of many roads to God.