From the earliest days of Christianity, followers of Christ have insisted that Jesus is fully divine — that He is God incarnate. Today, many people are willing to accept that Jesus was a wise human teacher or even a prophet. But they struggle with the idea that Jesus is also God.
The deity of Christ is absolutely essential for us. Without it, we don’t have the revelation of God that we have in Christ. We have in Christ, God revealing himself to us in a way that we can understand as God takes on human flesh. We also, in Christ, have a God who’s able to take on the sins of the world. He’s human, fully and completely human, but he also is fully and completely divine and therefore able to show us who God is and redeem us.
The doctrine of Christ’s divinity is central to even our definition of who Christians are. Christians are “Christ ones,” and without the central declarations of Christianity, which are, “Christ has died; Christ is risen; Christ will come again” — these are the central foundational things that we believe about who we are — and without that, we are people who follow a great teacher who had some individual and unique things to say, but to whom we can compare other teachers and maybe synthesise a philosophy of our own. However the divinity of Christ says, because He is Lord, because He is God, what He says about himself and about who we are and what the way of salvation is, is authoritative and final. And so He defines who we are in ourselves as Christians. And Christianity is definitely Jesus. Without Jesus it would not exist, and apart from his divinity and lordship, it has no reason to exist except as a historical philosophy.
The doctrine of Christ’s divinity, is essential to all Christian faith. Jesus Christ is a real human being, and we can relate to him as human beings to another human being. But the New Testament is quite clear that He is more than just a human being. So it could be the epistles of the New Testament, the earliest parts of the New Testament, they all describe Jesus as divine. And in the Gospels too, there is a clear teaching that he is authoritative and has the identity with God. So quite clearly, at several places in the New Testament, to actually believe in Jesus Christ is to believe in him as Lord.
There’s many an affirmation of the deity of Christ in the New Testament. For example, John 1:1, “In the beginning was the Word, and the Word was with God, and the Word was God.” then an inclusio with that in John 20:28, where Thomas says of Jesus, “My Lord and my God.” Paul, in Titus 2:13, talks about the glory of “our great God and Savior, Jesus Christ.” Going back to Romans 10:9, Paul says, “If you confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead, you shall be saved.” And then in verse 13 he says, “Whoever calls upon the name of the Lord shall be saved.” And there he’s quoting from the prophecy of Joel, and “Lord” there is Yahweh, the God of Israel. So you confess that Jesus Christ is Lord, and he’s there given the sacred name of the God of Israel.
In his classic work, Cur Deus Homo: Why Did God Become a Man, Anselm says that the, the one who atones for sin must be both God and man, because only God can atone for sin, and only a human being ought to. So Jesus is the God-man. And then, another reason is that only God can fully reveal God. So, going back to John 1, “the Word was with God, and the Word was God.” And then in verse 14, “The Word became flesh and dwelt among us, and we beheld his glory.” So he was God and he became flesh, but he didn’t cease to be God when he became flesh.