The unthinkable happens. You had hoped and prayed for this day, but never expected it. The Holy Spirit worked in a friend’s heart, and he put his trust in Christ as Savior. “I never thought this would happen,” you mutter. “What do I do next?”
Many times, we are guilty of witnessing without expecting a particular friend to trust in Christ as Savior. Yet, the Holy Spirit works in surprising ways. When a friend puts his trust in Christ, it is important to follow-up with him and to give some instruction in the core doctrines of Christianity. One of those areas is in Christology, specifically the deity and humanity of Christ. In order for Christ to save us from the consequences of our sin, he must be fully God and fully man.
Why must Christ be God?
Dr. John Hannah well explains the necessity for Christ’s deity, “A lesser cannot satisfy a greater if the criteria of the greater is the perfect character of who He is.” In other words, everything that God is must also be everything that Jesus is. A finite being is not capable of taking all of our punishment upon himself.
An infinitely perfect sacrifice is needed to satisfy the infinite wrath of an infinite God. Many Scriptures assure us of Christ’s sinlessness and perfection. The Apostle Paul said, “For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.” (2 Cor. 5:21) Peter described him as one “who committed no sin” (1 Pet. 2:22) and as a “lamb without blemish and without spot.” (1 Pet. 1:19) The author of Hebrews described Christ as being the “radiance of God’s glory and the exact representation of his being.” (1:3 NIV)
Why must Christ be man?
As important as it is for Christ to be fully God, He must also be fully human. It was necessary for Him to be a human in order to take our place. Hebrews 2:16-17 explains this concept, “For indeed He does not give aid to angels, but He does give aid to the seed of Abraham. Therefore, in all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make propitiation for the sins of the people.”
In being a man, Jesus is also able to fully represent us as it states in Romans 5:19, “For as by one man’s disobedience many were made sinners, so also by one Man’s obedience many will be made righteous.” Again, in 1 Timothy, 2:5 it says, “For there is one God and one Mediator between God and men, the Man Christ Jesus.”
Why must Christ be fully God and Man simultaneously?
It can be difficult for some to conceive of Christ as being God. A Muslim friend told me recently, “I can’t conceive of God condescending Himself by sending His Son to be born as human.” Others have had the opposite problem, saying that Christ was God but only appeared to be human. Still others have seen Christ as being a mix of both, part God and part man.
The first two beliefs are more readily problematic. It can be harder to argue with someone who sees Jesus as an intermingling of God and man, because as strange as it is for Christ to be both God and man, it is even stranger to believe that he is fully, one hundred percent both simultaneously. And yet, as strange as that may seem, that is precisely the case.
If Christ were not fully God and fully man, there would be no salvation for mankind. Being part man and part God, would make Him more than man and less than God. A being less than God could not take the penalty for our sins. A being that was only part human could not represent us as a substitute. Christ’s full humanity and full deity is an essential and integral part of the atonement.