First, leave "Calvinist" behind. It is not part of this discussion and will only muddy the waters. You mention Calvinism a lot. Calvinists are a small portion of Christianity and that discussion is only going to confuse discussion here.
:nono: Not true. The early Church fathers began formulating ideas of what they believed. While it is understandable that one will wrestle with ideas presented in scripture, the church councils came to classify what scripture allows and what is outside of the parameters of those scriptures. As I've given above, the two truths are: One that scripture is abundantly clear that there is only one God and scripture is abundantly clear the Father, Son, and Spirit are/is God. Logic? It is simply to take scripture at its face value and neither ADD nor SUBTRACT from them, whether it SEEMS logically tenable to do something. Why? Because logic on this side is from man. Revelation is from God thus it was at the time of the councils, forbidden to go beyond or trounce upon, any scriptures God has given. Good rule, no? (yes, we don't want to even attempt to trample God with anything we believe).
If revisionist history is given its head, then there are all kinds of problematic take-aways from the revision. All books, even by orthodox theologians were forbidden at that time. Only church sanctioned books were allowed. Next, not all the books were destroyed, a good many circulated BUT the people were not literate so even those books were not available to the masses. Be careful with your indictments and only go so far as actual offenses allow. Next, there is a 'suspicion' in academic circles about how we have two different set of texts. While you may suggest that the scritpures were twisted, this isn't true. What is true of all texts is that some verses are left out. This does not indicate adding or revision. We've no idea what happened, can but make educated guesses. That's it. You cannot go further without it being untenable and generally a lie/inaccuracy. You don't want to change your position based off of even an exaggeration, because an exaggeration is not of God. It means, if you use this particular 'third problem' for changing, you are doing so upon an exaggeration.
This is just called language. A good many of the terms DO exist in the bible if you understand the term. For instance: Omnipotence. Is it in the bible? No, not "Omnipotence" but its equal "Almighty" is and that is exactly what omnipotence means. All it would take is for a translator to put "Omnipotence" in a bible in place of "Almighty." Then it'd be in a bible but Omnipotence IS, in fact a biblical term and taken directly from the Bible. Trinity likewise is not given, but "Godhead" is, and "I and the Father are one" is.
This is modalism: equating the Father as the Son. Your problem isn't a square circle, it is how you are able to grasp truths given in scripture whether you can explain them or not. There are many things given in scripture I cannot explain. I cannot explain God's eternal non-beginning. I cannot explain how the physical world came from Spirit. It doesn't mean I'm not intelligent or that I'm ignoring answers. Part of our Faith, is faith. A trust in God where I cannot rely upon myself. The Lord Jesus Christ is the Only Way to the Father.
Question: If I give someone a scripture, and they do not believe it, though it is in the Bible, does that make the person a Christian? Are they trusting God? Are they trusting Christ when they throw out that one scripture, whatever it may be? Would I say "going to hell?" I believe the problem is willful disregard for something God said, and it certainly is a problem. Does it condemn one to hell? I'd think rather, that God will bring about the change needed. The Holy Spirit indwells and guides His own, and so I don't think one with Him inside can resist for very long. Who can argue with God? The Lord Jesus Christ said He'd guide us into all truth.
Stop doing both? The issue is to know scriptures and continue to follow the Spirit's guidance in your life. He is not going to cause you to be in friction with the majority of the Body of Christ, that doesn't make sense but a good many heterodox and worse, fall exactly in that category. The Holy Spirit led Martin Luther, not to abandon the church, but to love it and try to reform it. The separation happened because Catholics forced the separation.
It isn't important what you decide, but rather if and as the Holy Spirit leads. He can and does, only lead in truth. If you are growing bitter, less loving toward the Body of Christ, it is a sign you probably aren't being led by the Spirit into all truth. Truth is the only direction He leads. I believe the scriptures given in the
Triune thread and believe they are clear.