How can we best understand who Jesus Christ is and what he means for us?
Some say that Jesus is “one mind, one soul, one being, as truly one as we are, and equally distinct from the one God” . Some say it is “incoherent or self-contradictory” to affirm Jesus is fully God and fully man, similar to claiming that a circle is really a square . Some say Jesus was a human being especially open to God’s workings .
This question is important for the church’s ministry because the Church has been entrusted with the task of proclaiming the good news of what Jesus has done in His death and resurrection. Christians have long held that only God can save humanity, but only a human can offer a sacrifice for human sin. It is necessary that the Savior be both divine and human. The Church also worships Jesus, affirming His divinity. If Jesus is not divine, the Church is guilty of idolatry. The Church’s mission and worshiping identity are defined by who Jesus is.
Scripture says that Jesus is both human and divine. The Gospel of John begins: "In the beginning was the Word, and the Word was with God, and the Word was God….And the Word became flesh and lived among us, and we have seen his glory, the glory as of a father’s only son, full of grace and truth….The law indeed was given through Moses; grace and truth came through Jesus Christ. No one has ever seen God. It is God the only Son, who is close to the Father’s heart, who has made him known" .
The Epistle to the Hebrews says, "Since, then, we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast to our confession. For we do not have a high priest who is unable to sympathize with our weaknesses, but we have one who in every respect has been tested as we are, yet without sin" .
St. Paul wrote, "For in [Christ] the whole fullness of deity dwells bodily” . He also wrote: "Though he was in the form of God, did not regard equality with God as something to be exploited, but emptied himself, taking the form of a slave, being born in human likeness. And being found in human form, he humbled himself and became obedient to the point of death—even death on a cross" .
The Christian tradition has consistently affirmed that Jesus is fully God and fully man. St. Irenaeus of Lyon, writing only two generations after St. John, believed Jesus’ dual nature was necessary for salvation: “For unless man had overcome the enemy of man, the enemy would not have been legitimately vanquished. And again: unless it had been God who had freely given salvation, we could never have possessed it securely” . The Church declared at the Council of Nicaea in 325 and reaffirmed at the Council of Constantinople in 381 that Jesus is "of one substance with the Father…and was incarnate by the Holy Ghost and of the Virgin Mary, and was made man”. In the years following Nicaea, St. Athanasius of Alexandria wrote: “The Word of God took a body and used a human instrument, in order to give life to the body and in order that, just as he is known in creation by his works, so also he might act in a human being, and show himself everywhere, leaving nothing barren of his divinity and knowledge” . The Council of Chalcedon in 451 confessed “one and the same Son, our Lord Jesus Christ, the same perfect in Godhead and also perfect in manhood; truly God and truly man”.
During the doctrinal disputes of the Protestant Reformation, the Reformers continued to affirm Jesus as fully God and fully man. John Calvin insisted, “since neither as God alone could he feel death, nor as man alone could he overcome it, he coupled human nature with divine that to atone for sin he might submit the weakness of the one to death; and that, wrestling with death by the power of the other nature, he might win victory for us” .
Even in the modern era, the Church affirms the full humanity and divinity of Jesus across the ecclesial spectrum. Karl Barth declared it was essential for Jesus to be both God and man if humanity is ever to know God at all: “It is only when we look at Jesus Christ that we succeed…in speaking about God in the highest; because it is here that we get to know man in the covenant with this God, in His concrete form as this man” . The Catholic Church also declares, “He became truly man while remaining truly God” .
I believe that Jesus is fully God and fully man. In Him, God unites Himself to humanity. God the Son has reached out to humanity and imparted to us His divine life. The fact that God the Son has become a man means humanity has been made able to enjoy life with God. I can think of no more certain comfort than this. Yet I still do not understand the details of how these two natures coexisted. How can the omniscient God “not know” ? Could He have sinned? Was there tension between His humanity and divinity during His anguish before the Passion?
 Channing, William Ellery. "Unitarian Christianity." In The Works of William E. Channing, D.D., 367-83. Boston, MA: American Unitarian Association, 1888, p. 373.
 Feenstra, Ronald. "Incarnation." In A Companion to Philosophy of Religion, 532-40. Blackwell Publishers, 1997, p. 535.
 John 1:1, 14, 17-18 NRSV.
 Hebrews 4:14-15.
 Colossians 2:9.
 Philippians 2:6-8.
 St. Iranaeus of Lyon. "Against Heresies." Vol. 1. The Ante-Nicene Fathers. Grand Rapids, MI: W.B. Eerdmans, 1996, 3.18.7.
 St. Athanasius of Alexandria, and John Behr. On the Incarnation. Yonkers, NY: St Vladimir’s Seminary Press, 2011, p. 98.
 Calvin, John, John T. McNeill, and Ford Lewis Battles. Institutes of the Christian Religion. Louisville, KY: Westminster John Knox Press, 2011. 2.12.3.
 Barth, Karl. Dogmatics in Outline. New York, NY: Harper & Row, 1959. p. 69.
 Catechism of the Catholic Church. Liguori, MO: Liguori, 1994. p. 117.
 Matthew 24:36.