I appreciate the idea that our human terms and language cannot possibly describe the nature of God. Our definitions fall far short of being even remotely close to accurately describing the nature of God...what God is. This is the reason I baulk at accepting the commonly accepted formula of the trinity, as offered to us by the church; whether a direct quote from Nicea, or a slightly altered version. Because the trinity is just that...a formula created by man to describe God...which I believe is impossible.
However, while we may not be able to describe what God is, I believe we most assuredly have sufficient evidence to accurately relate to others the identity of God...Who God is. That evidence we find in scripture. And it is given in language we can understand, and in terms we are meant to understand, because the definitions of those terms were born in the mind and heart of our Creator, in Whose likeness we were made. That evidence in in scripture. In fact, it is the only place we should look. Councils in history were riven with controversy and doubtful motives...what conclusions those councils came up with must be treated with suspicion, and ought never to be used, as has been done and is still currently being done, as rock solid dogma that must be believed if one is to be accepted into the community of faith.
There are not that many scriptures which identify God, considering the scope of scripture, but what there is, are clear.
John 17:3...the words and testimony of Jesus Himself to His Father...and this is life eternal, that they might know Thee, the only true God, and Jesus Christ Whom Thou hast sent.
1 Corinthians 8:6...the words and testimony of the apostle Paul in informing pagan idolaters who the true God really is...But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him.
Acts 8:37; John6:68,69; John1:34,49; Matthew14:33; John20:31; from all these, and many more, we are informed that God had a Son, and His Son's name is Jesus. We are also informed that believing this truth, is the foundation of our faith leading to salvation...Acts9:19,20; Isaiah9:6; John3:16; Galatians 4:4; 1John4:9,10; 1John4:14.
Our natural God-given wisdom also informs us that the Son is of the same nature as His Father. Like Father like Son right? Me, being human, even before I have any children, assumes my own sons are also human. And guess what, joy oh joy, they are. And praise God, so also are my daughters. Why ought we accept anything other than that basic fundamental truth, that like begets like in relation to God and His Son? So the Son must also be God, right? Scripture clearly confirms this also, Jesus Himself testifying to His own divinity.
Finally, the Son clearly pre-existed creation, for scripture declares that all things were made by and for Him, the Word made flesh. The Word was in the beginning (John1:1,2) but in the beginning of what? The earth? Creation? No, because the Word pre-existed those things which were made. Could it be rightly said that when the Word was, this was the beginning? Colossians1:15 describes Jesus as the firstborn of every creature, can this refer to the incarnatrion?, no, because the very next verse says by HIm (the firstborn) were all things created. This is the same that is taught in John1:3, confirmed by Col.1:17 saying that He (the firstborn) is before all things.
I know many like to go beyond the above, in attempting to describe the relationship between Father and Son, by using for example John10:30.
But John10:30 must be viewed and considered in relation to other verses such as John14:28. Also one must take careful note of the subtle differences between John8:58 and John10:36. And what of the significance of Acts3:13?