My Reformation Study Bible, ed. by R.C. Sproul, Sr., (Nashville, TN: Thomas Nelson, 1995) offers an exposition upon “Jesus Christ, God and Man” (p. 1660). Therein it notes:
Trinity and Incarnation belong together. The doctrine of Trinity declares that Christ is truly divine; the doctrine of the Incarnation declares that the same Christ is also fully human. Together they proclaim the full reality of the Savior revealed in the New Testament, the Son who came from the Father’s side at the Father’s will to become the sinner’s suitable substitute on the cross (Matt. 20:28; 26:36-46; John 1:29; 3:13-17; Rom. 5:8; 8:32; 2 Cor. 5:19-21; 8:9; Phil. 2:5-8).
The doctrine of the Trinity was defined at the Council of Nicaea (A.D. 325), when the church countered the Arian idea that Jesus was God’s first and noblest creature by affirming that He was of the same “substance” or “essence” as the Father. The distinction between Father and Son is within the divine unity, so that the Son is God in the same sense as the Father is. In saying that Son and Father are “of one substance,” and that “the Son is begotten, not made” (echoing “only begotten,” John 1:14, 18; 3:16, 18), the Nicene Creed unequivocally recognized the deity of Jesus Christ.
The church’s confession of the doctrine of the Incarnation was expressed at the Council of Chalcedon (A.D. 451), where the church countered both the Nestorian idea that Jesus was two “persons,” not one, and the Eutychian idea that Jesus’ divinity had swallowed up his humanity. Rejecting both, the Council affirmed that Jesus is one person in two natures (that is, with two sets of capacities for experience, expression, and action.) The two natures are united in Him without mixture, confusion, separation, or division, and each nature retains its own attributes. In other words, all that is in us, as well as all that is in God, is and always will be truly distinguishably present in Christ. Thus the Chalcedonian formula strongly affirms the full humanity of the Lord.
The Incarnation, the mysterious miracle at the heart of historic Christianity, is central in the New Testament witness. Jesus came first to the Jews, whose central affirmation of faith is that there is only one God. The apostles were Israelites, yet the and the writers of the New Testament taught that Jesus the Messiah should be worshipped and trusted. This is to say that He is God no less than He is man. Tit is amazing that this testimony could prevail among them.
John’s Gospel opens its eye-witness narratives (John 1:14; 19:35; 21:24) with the declaration that Jesus is the eternal divine Logos, agent of creation and the source of all light (John 1:1-5; 1:9). Through becoming “flesh,” the Logos was revealed as the Son of God and the source of “grace and truth,” “the only begotten of the Father” (1:14; 1:18). The Gospel is punctuated with “I am” statements that have special significance because “I am” was used as a divine name on account of the Greek translation of Ex. 3:14; when John reveals Jesus as the “I am,” the claim to deity is explicit. Examples of this are John 8:28, 58, and the seven declarations of Jesus as (2) the bread of life, giving spiritual food (John 6:35, 48, 51); (b) the light of the world, banishing darkness (John 8:12; 9:5); (c) the door for the sheep, giving access to God (John 10:7, 9); the good shepherd, protecting from peril (John 10:11, 14); (e) the resurrection and the life, overcoming death; (f) the way, truth, and the life, guiding to the Father (John 14:6); (g) the true vine, nurturing for fruitfulness (John 15:1, 5). Climatically, Thomas worships Jesus as “My Lord and my God” (John 20:28). Jesus pronounces His blessing on all who share Thomas’ faith (John 20:29-31).
Pau says about Jesus that “in Him dwells all the fullness of the Godhead bodily” (Col 2:9; c.f. 1:9). Paul hails Jesus the Son as the Father’s image and as His agent in creating and upholding everything (Col. 1:15-17). Paul declares Him to be “Lord,” to whom one must pray for salvation just as one calls on Yahweh (Joel 2:32; Rom. 9:10-13). Jesus is “God over all” (Rom. 9:5), our “God and Savior” (Titus 2:13). Paul prays to Him personally (2 Cor. 12:8, 9), and looks to Him as the source of divine grace (2 Cor. 13:14). The testimony is explicit: faith in Jesus’ deity is basic to Paul’s theology and religion.