Trinitarians and those who reject the Trinity but who otherwise believe that Jesus was/is God typically cite John 1:1 as the absolute proof of their belief.
John 1:1 states: “In the beginning was the Word, and the Word was with God, and the Word was God.”
First, though, it ought to be noted that nowhere in the text or surrounding context (or anywhere else in the Bible for that matter) is there any mention of the holy spirit being part of a three-in-one godhead. Although the verse is cited to prove that the Word is God Almighty one frequently overlooked aspect of the verse is the opening phrase: “In the beginning.” The question ought to be asked: In the beginning of what? Since Jehovah God describes himself as the King of eternity, having no beginning or end, it is inappropriate and meaningless to refer to the beginning in relation to God. So, what does “in the beginning” mean? What is the significance of that phrase?
Those familiar with the entire Bible will undoubtedly recognize the phrase “in the beginning” as also being the very first words of Genesis: “In the beginning God created the heavens and the earth.” The beginning of Genesis 1:1 is in reference to an actual beginning, in this case, the beginning of the creation of the physical universe. Science now generally agrees with the statement of Genesis that the universe had a beginning, what is called the Big Bang. So, since the phrase at Genesis 1:1 is in regards to something that actually began, should not John 1:1 be similarly understood? But, again, since God had no beginning why does John use the same expression as is found in Genesis?
The key to unlock this mystery is found at Job 38:7. That is where God asked Job where he happened to be when the earth was created, when all the angels shouted in applause of God’s great work. Ah, so, there were intelligent beings in heaven before the earth was created. This means that Genesis 1:1 is not an absolute statement but is only relative to the cosmos. There is another world that exists outside the physical realm. And that world was created before the material universe that we inhabit. So, the “in the beginning” of John 1:1 must be understood to be in reference to the absolute beginning of all creation.
Although it is humanly incomprehensible, the truth revealed in the Scriptures is that God had no beginning. He has always existed. He will always exist. He is timeless – outside the restrictions and limitations imposed upon his creation. And it really plays havoc upon the fragile mind that tries to grasp how God could have been alone forever and ever even though at some point he became the Creator. Let’s just leave that thought alone. But we can understand the concept, at least, that God decided to start a family. And the first creature that came into existence was called the Word. That is why it says, “In the beginning was the Word.” The entity that eventually became the man, Jesus, was the firstborn Son of God. In fact, at Colossians 1:15 Paul said that Jesus was the firstborn of all creation. (New American Standard Bible)
Jesus is also called the only-begotten son.” What does that expression mean? The Greek Scriptures use the expression monogenes in connection with sons or daughters who were the only child of a parent(s). Why should it be any different with Jesus? But how was Jesus the only child of God? He was the only son of God, in that, he was the first and only creature that God directly created, because after God begot the Word he then gave him the privilege and power to create all other things. That is why, for example, in Genesis God stated: “Let us make man in our image.”
Being made in God’s image and exact representation of God the firstborn of all creation could righty speak for God; hence, the Word.