Your understanding of 1 Cor 8:6 contradicts your understanding of John 1, if I'm understanding you correctly. You believe the Word (Jesus) was God, but 1 Cor 8:6 says there is only one God, the Father, not the Son.
As typically happens, anti-trinitarians read just half of 1 Cor 8:6, ignoring the implications of the logic of the first half and the implications of the second.
1Co 8:6 yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist. (ESV)
You say that this verse "says there is only one God, the Father, not the Son." But that is not all this verse says, is it? Looking fully at what it states: "one God the Father,
from whom are all things...one Lord, Jesus Christ,
through whom are all things."
That is in full agreement with John 1:3, All things were made through him, and without him was not any thing made that was made. (ESV), and Col 1:16, For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities--all things were created through him and for him. (ESV)
All three state the exact same thing about Jesus. If all things (which is referring to all created things)
come from the Father, and this speaks of his always having existed, then the statement that all things (everything that has come into existence)
come through Jesus, then the only logical conclusion is that Jesus cannot have been created, or Paul (inspired by God nonetheless) is lying.
Similarly, in John, if everything that was made was not made without the Word, then again, the only logical conclusion is that the Word was not made. And the same can also be said about Col 1:16. The similarities between John's and Paul's statements are abundantly clear, particularly when we consider John 1:14:
Joh 1:14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. (ESV)
The Word is the Son and the Son is Jesus, who has always existed in some form, just like his Father.
As for "one God, the Father" and "one Lord, Jesus Christ," if one excludes Jesus from being God, the one necessarily excludes the Father from being Lord. This is actually Paul's expansion of the Shema.
You also said the Son is not the Father. Therefore, you have two Gods. As I understand it, there is only one God, Father Yahweh. He brought His Son into existence the same way He brought creation into existence, by speaking His word.
Not two Gods; two Persons, one God. Monotheism is a foundational tenet of the Christian faith. Please provide a verse which shows that the Father brought the Son into existence "by speaking His word."
The Greek of Col 1:16 is rendered "in him" in other versions rather than "by him". There is only one Creator who created everything by Himself, Father Yahweh:
Isa 44:24 Thus saith YHWH, thy redeemer, and He that formed thee from the womb, I am YHWH that maketh all things; that stretcheth forth the heavens alone; that spreadeth abroad the earth by myself;
This is what is known as begging the question. You are assuming the very thing you conclude, namely, that Yahweh is only the Father. As for how Col 1:16 is rendered in that regard, it makes no difference to what is said.
Phil 2:5-8 says nothing about the Son being the "Word".
No, but I never said it did, but it does say several significant things to us including the existence of Jesus as God. It is a passage that makes clear the Incarnation.