gty.org/resources/sermons/43-6
The gospel of John--we're in chapter 1, working our way through this wonderful presentation of Christ, remembering that John's purpose is very simple. His purpose, which is articulated at the end of the book, is to present the evidences, the testimony, the proof that that Jesus is the Messiah, the Son of God, so that you might believe and believing have eternal life in His name. His goal, as I said before, first of all polemic, to prove that Jesus is the Messiah, the Son of God; and then evangelistic, so that you in believing that may have the eternal life that comes with that faith. That's the whole point of the gospel of John. It is evidences of the deity of Jesus Christ, evidences of the messiahship of Christ, evidence that He is the Savior, the only Savior, and that those who believe in Him have forgiveness and eternal life.
So the gospel of John is in the opening eighteen verses a declaration of the deity of Christ. And then starting in verse 19, the evidences proving that declaration to be true. John opens the gospel, as you remember, speaking of the Lord Jesus as the Word and identifying Him as with God and God Himself. He is both God and with God, which is a Trinitarian understanding. He is fully God, and yet He is with God. The members of the Trinity are fully God and yet separate persons. He introduces Him not only as the Word, that is the truth that emanates from deity, but as the life, the very life source of all that lives, and then as light, and that is to say He is God penetrating the darkness of a fallen world....