Terry,
All along have read your reflections avidly on the basis that you are on to something - whether I'm entirely in agreement or not. But this one is particularly good. As an outsider looking in on the phenomenon of JW, it appears to me quite often as a shape shifter. But your working thesis looks like a possible way to pin it to the wall. So take my comments below as explorations or a maybe a couple of refinements (e.g., dissent origins).
Had I been living 400 years ago and confronted on the question of the Trinity, I would have kept my head down. Today, looking at the controversy, I would rather say that I can sympathize with the debaters about how how difficult it is to sort out such a dilemma by studying what's recorded in scriptures. And then looking at established churches today, I sense that many behave much the same. Despite the importance of Jesus Christ in say the theology and day to day teachings of Baptists, to give one example, as near as I can tell they originated with the teachings of a certain Arminius in the Netherlands who it would be difficult to claim in the ranks of the Trinitarians. So, if they are confused or confusing, why shouldn't I be as well?
But Christianity is also a philosophy of life. There is a Pre and Post Christ measure of things - and we happen to live in the after period. Our conduct is measured in what would Christ say, do or think - and our society here did not form until after Augustine had written his City of God. A universal church and a city of God were much akin to establishment of a caliphate that followers of Muhammad would institute a few centuries later. It was an attempt to order life on earth until Christ's return, either as implied in Gospels, Epistles, Revelations or some combination thereof. Paul and Peter's interpretations were more administrative day to day. Something like Hebrews would be higher flying.
Now flash forward 1500 years and we find that in western Europe there was a pervasive feeling that the society was corrupt and erring - and democratization of the scriptures would engage more of the population in solving problems. It wasn't that the Bible was not read. It was read in special editions and distribution was limited. Moreover, what histories of the Renaissance subtly describe, western Europeans generally did not understand Greek. They often got their Greek classics after they were translated from Arabic to Latin via Andalusia. Who had time to write, much less approve vernacular translations even if the clerical and civil authorities had been well disposed toward them?
But it happened and the result was something like a vampire movie. The townsmen/reformers used the Book much like the vampire killers would use a crucifix to ward off a vampire; in this case it was the established church.
Everything was in the Old and New Testament. Every abuse of the present day could be fought with a Biblical citation. And consequently, everything that happened within the interval between the first and 16th century that was assumed a part of the City of God was now relegated to illegitimacy or to nothing. Who was more important? King David in Kings campaigning against Saul or Thomas Aquinas attempting to summarize the knowledge of God? To test this question, monitor fundamentalist radio broadcasts for a few hours.
And then, when you examine the editing of the original scriptures, you have to wonder if this did not happen before( circa 700 to 400 BC and onward) as well.