John, the Gospel, is full of Christology because all correct theology begins and ends with Christ. John, the author, correctly understands that a distortion in understanding who Christ is is the most dangerous thing that can happen to the church. John wastes no time in getting started with Christology in the Gospel. By the fourth verse, John has already made a statement that is going to be carried throughout the rest of the text, “In him was life, and the life was the light of men” (John 1:4, ESV). Unfortunately, this verse is often only connected with the creation theme of the first Chapter, and while it is certainly true that that section is addressing the very timeless creative power of God revealed in Christ, the second person of the Trinity, there is more to this statement. The life that is the light is a theme that runs throughout the Gospel. In Chapter six Jesus says “I am the bread of life; whoever comes to me shall not hunger, and whoever believes in me shall never thirst” (John 6:35, ESV). Later Jesus says, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life” (John 8:12, ESV). Notice the theme across all of these texts is life and light. All of these statements are pointing to two primary things. First, as Okorie states, they are pointers to “Jesus’ divine nature” (Okorie, 2001, p. 486). Second, they are establishing the nature of Christ as the only one needed for men to have light and life. In the first century, the church dealt with Gnosticism. Gnosticism is many things and even varied among the groups of Gnostics. However, the primary claim of the Gnostic teachers was that they possessed knowledge about God that others did not and the only way to know this knowledge was to be discipled by them (Borchert, 1988). Jesus says, I am enough; I am the light, I am the life, and I am the bread, because he is enough, there is no need for Gnostic teachers to bring anything else to the flock, no matter if those Gnostic teachers are historical or modern.
“In him was life, and the life was the light of men” (John 1:4, ESV). Kruse puts it this way “Word shares in deity, he shares in the life of God” (Kruse, 2003, p. 64). What does this attribute to Jesus is the next logical question that comes from a statement like this. If Christ shares in divinity, to what extent is that divinity in Christ? Or, more practically, to what extent can that divinity be experienced in Christ? This experience found personally in Christ is the main point of John’s Christology. “I am the bread of life” (John 6:35, ESV). “Jesus explicitly identified himself as ‘the bread of life” (Kruse, 2003, p. 170). Again this is pointing to the experience found personally in Christ. There is no indication that John is saying there is anything needed for life and light other than Jesus. “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life” (John 8:12, ESV). It is fascinating how this I am statements by Christ is so similar to the prologue. John’s intent of displaying a finished work in Christ, a sufficiency in the experience of Christ, is seen in the link between the prologue and statements like this one.
Gnosticism got an early start in the church, and it is clear that the best defense against it, as seen by both Paul and John, was the divinity of Christ. John’s Gospel focuses on the divinity of Christ, and so does Paul’s Colossians. Other texts, such as Jude, also deal with the Gnostic teaching. It can easily be argued that the main theme in John is Christ. It seems clear that the author has a lot placed on the sufficiency of Christ and a reasonable explanation of this emphasis is to combat Gnostic teachings. Gnostic teachings that, at their core, would draw the flock away from leaning on Christ alone and instead put their faith in the teachings of men. Christology in John could not be more tuned to the task of teaching Christ alone.
All good historical studies end in application. John’s Christology has a practical application with the cults that have changed the deity/nature of Christ. Both the Jehovah Witnesses and Mormon cults have many similarities with Gnosticism. Both have sources that claim to know something other than the Bible, additional knowledge, that is needed to serve God rightly. Though fairly, neither Jehovah Witnesses nor Mormons would connect themselves with Gnosticism. However, they will straightforwardly say they have information about serving God beyond the Bible. This means the work of John’s Gospel is much needed today. A proper Christology is the only response to an improper one.
At the beginning of John’s Gospel, John starts at the beginning. This is because Jesus, this Logos, this Word, was at the beginning. John goes on to develop the understanding in his readers that this Word is the life and the light of men. There is no need for more, Jesus is enough.

Borchert, G. L. (1988). Gnosticism. In Baker encyclopedia of the Bible (Vol. 1, p. 873). Grand Rapids, MI: Baker Book House.
Kruse, C. G. (2003). John: an introduction and commentary (Vol. 4, p. 64). Downers Grove, IL: InterVarsity Press.
Nolland, J. (2011). The thought in John 1:3c-4. Tyndale Bulletin, 62(2), 295-311.
Okorie, A. M. (2001). The self-revelation of Jesus in the ‘I am’ sayings of John’s Gospel. Currents In Theology And Mission, 28(5), 486-490.