The question of the relevance of Christ’s deity ultimately asks a much more foundational question. Is God’s Word sufficient for yesterday, today and forever? Paul writes in his second letter to Timothy, “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness.” (2 Tim 3:16 (English Standard Version)) As one looks at Scripture we must stand on the foundation that God has spoken, literally “breathed out,” and the canon is closed. If this is not the case, then one is to assert that Jesus is God today but tomorrow, a new revelation could change our view on the matter. We see this very thing happening in many cults, not just in times past, but also today in our neighbors, our workplaces, and even in our churches. Today, Jehovah’s Witnesses are some of the most noted people who deny the deity of the Son and yet continue to align themselves with the “Christian” title.
So, how is this doctrine relevant for today? Millard J. Erickson writes, “For since Christians are by definition believers in and followers of Christ, their understanding of Christ must be central and determinative of the very character of the Christian faith.” The deity of Christ is central to the Christian faith and to deny a central truth of the Christian faith is to deny the very subject of the Christian faith, namely Jesus Christ.
Jesus, in His own words to the Samaritan woman, says, “God is spirit, and those who worship him must worship him in spirit and in truth.” (John 4:24) This is a basis for answering the question of relevance and the follow up question, “can a person be saved and still deny the deity of Christ?” Jesus’ own words offer a very direct answer to these questions. For one to worship God, it must be done in spirit and in truth. His response has defined for us what is truth. “Truly, truly, I say to you, before Abraham was, I AM.” (John 8:58) Jesus took on the very name that God the Father used solely for Himself in Exodus 3. Jesus also tells the Jewish crowd in John, “I and the Father are one,” (John 10:30) to which the Jewish leaders responded by picking up stones to stone him for blasphemy.
There are many today who would claim to be saved and yet deny the deity of Jesus. To deny His deity is to deny the basis of our salvation. Yet, by the very words of Jesus, “I am the way, the truth and the life. No one comes to the Father except through me.” (John 14:6) To deny His deity is to deny who Jesus claimed to be and therefore, it follows that one who denies His deity worships a false Christ. Paul warns against this very thing when he writes, “for if someone comes and proclaims another Jesus than the one we proclaimed…you put up with it readily enough,” (2 Cor 11:4) and again, “if anyone is preaching to you a gospel contrary to the one you received, let him be accursed.” (Gal 1:9) Warning after warning is given in the New Testament against following a false Christ. When Jesus responds to Satan in the midst of temptation, He explains that God alone is to be served. He alone is to be worshipped. (Matt 4:10) Yet, Jesus accepts worship when Thomas exclaims, “My Lord and my God.” (John 20:28) To worship the person of Christ is to worship the triune God of Scripture. To worship a created being, that being an elevated person, but not deity, is to worship creation over the Creator. So to deny the fully God, fully human person of Christ is to worship a false Christ. To worship God in spirit and in truth is to worship Him, as He exists, not as we would like for Him to be.  It is to worship an idol of our own making.
So why is this doctrine relevant? As there are many who would deny the deity of Jesus and still claim to be Christians, we are called to confront heresy with the truth; the truth that Jesus is fully man and fully God, “for in him the whole fullness of deity dwells bodily.” (Col 2:9)
To confront this heresy, we must teach, even at a young age, this doctrine with clarity and resolve. To describe the deity and humanity of Jesus is no small task, yet we must begin with a basic understanding of the Trinity. James R. White defines the Trinity this way, “Within the one Being that is God, there exists eternally three coequal and coeternal persons, namely, the Father, the Son, and the Holy Spirit.” First, we understand that there is only one Being of God, but three persons share this one Being. Second, we see that the three persons are not only coequal, but also coeternal. This is essential to understand that Jesus Christ not only is God, but also has eternally existed as the second person of the Trinity. To continue to defend His deity, the prologue of John comes to mind. John 1:1 tells us of Jesus’ eternal nature by stating, “In the beginning was the Word.” The Greek rendering literally interprets this phrase as a continuous action in the past, with no point of origin. “The Word was with God,” translates from the Greek, “face to face” and “the Word was God,” tells us the Word “shared the nature and Being of God.” So a literal rendering of John 1:1 would say, “The Word has eternally existed, face to face with the Father, sharing the nature and Being of God.”
To explain the humanity of Christ, Paul writes in his letter to the church at Philippi, “Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant.”[Emphasis mine] (Phil 2:5-7) Paul here uses the same term as John, showing no point of origin in describing Jesus as, “in the form of God.” However, we will focus on a later phrase that points to his humanity. The phrase, “emptied himself” does not mean that He ceased to be God, but along side the next phrase, “taking the form”, shows us that Jesus “took on” human flesh. Paul uses the same word “form” in verses six and seven to emphasize He was eternally in the form, God, and took on another form, man, at the Incarnation. John uses the same language in his gospel when he says, “the Word became flesh and dwelt among us.” (John 1:14) There was at the same time, an emptying and a taking on. The emptying referring to Him voluntarily laying aside the privileges that were His, and the taking on of humanity. Jesus remained fully God while becoming fully human.
Because the Bible is the revelation of who God is, we must look solely to it as our source of truth in all matters of doctrine. One can conclude from Biblical evidence that Jesus is the eternal second person of the Godhead and yet, at the Incarnation, he took on the form of a servant. He took on humanity. Jesus is fully man and fully God. To deny either, is to deny the coequal, coeternal, second person of the trinity; Jesus Christ Himself.
 Millard J. Erickson, Introducing Christian Doctrine, 2nd ed. (Grand Rapids, MI: Baker Academic, 2001), 216.
 Ibid., 217.
 James R. White, The Forgotten Trinity (Minneapolis, MN: Bethany House Publishers, 1998) 18.
 Ibid., 50
 Ibid., 57
 Ibid., 125