Thank you, Pete.
I think what makes the Trinity and certain "traditional" doctrines so confusing for Jehovah's Witnesses, Mormons and other members (and ex-members) of NRMs from the Second Great Awakening is the type of indoctrination process and the isolationism that most of these groups pass off as "elitism." (Neither of which is good anyway.) What results is a form of individual incapacity to comprehend a major facet of the human experience, that is "spirituality."
In the Watchtower religion, indoctrination is carried out by means of never allowing members to be alone with a Bible without the presence of a guiding Watchtower publication. From the moment an individual is introduced to the religion, the member never reads Scripture without Watchtower guidance. They even yearn to read only a Watchtower "version" or a so-called "translation" of the Bible made up by the Watchtower religion.
What is really happening (and as described by outsiders who visit), Witnesses offer a "chain-reference" type of "reasoning" or logic-system/type of scholastic experience for their followers. Whether it's the introductory book used for main indoctrination or a Watchtower study or a public or Memorial season talk, Jehovah's Witnesses "make sense" of a topic by "linking" Scripture texts that might seemingly appear to logically settle a subject. Often they are merely using similar phrases or even words in English that seem to say something but don't in the original language that each sound or look the same in topical fashion to "prove" or support a view they might have, often collecting dizzying amount of these. The more texts they have in the list, the more "links" they have to make the "chain" stronger, thus the expression "chain-reference."
An illustration of this is the 1914/Daniel chapter 4 dream that uses Scripture texts from all over the Bible, from trees in one section, to the word year in another place, until they can "support" their personal belief that Jesus is ruling in heaven invisibly and that two groups make up but one generation and that are humanity is currently living in the Last Days. This is a perfect illustration of the "chain-reference" system that hops and jumps about the Bible, cutting and pasting passing references lit hit-and-run car scratches that one barely would notice while reading at first blush.
This system, unfortunately, often gets ingrained and stays in the minds of many of us even after we leave the Watchtower. While study is very important, religion in and of itself is not a scholastic exercise. There are scholars and academics called theologians of which the Watchtower has none, but religion is not made up of theologians. It is made up of spiritual people. And both Judaism and Christianity claims as its champions not sages and prophets but saints.
This is something that a person leaving a system like the Jehovah's Witnesses that is nothing but "read and study" system will find hard to deal with and find learning things like sacraments and miracles and the Trinity a hard thing to swallow. (And in reality we did not study--if you believed you were studying, you were lied to, we merely underlined things which was the equivlent of being fed vomit into our mouths by the Governing Body much like mother birds do for their baby birds. Personal study was not allowed in the world of the Watchtower religion, as all such activity would leave to being disfellowshipped eventually if this occurred--or leaving on ones own because you would have learned your were in a cult through actual academic research). One cannot be spiritual and grow to become holy. That would require getting to literally experience the Divine which would require moving past logic into the spiritual and the ineffable.There is nothing like that in the Watchtower experience.
So trying to make sense of the Trinity cannot be done by what is left over after the Watchtower created damage in its people, not immediately at least or with what little experience we had from that cult.
It is not the fault of the concept of the Trinity. Is it true? That is for us to discover. But we go about it in a wrong manner, like when we say: "Bible first." That is a Watchtower approach. It is not our fault when that happens either. It is an automatic reflex almost. We think, "Well, what else should we do?" Most of us have no other recourse. We have little experience with religion when you think about it.
Outside, people understand "mystery" as meaning a truth that comes from some spiritual source revealed via grace and responded to with love and personal faith. It doesn't sit well with someone who is used to sitting down and reading Watchtower concepts in a book and looking at up chain-references in the New World Translation and then underlining things with a yellow marker to ensure we "say things in our own words" later in a meeting.
But we are doing ourselves and those who believe in the Trinity a horrible wrong when we get angry at everyone but Jehovah's Witnesses for not comprehending or believing in the Trinity. We might never come to believe in it, and that is fine. It is incomprehensible not because the Trinity doesn't fit "the box." It doesn't seem to fit because we're too used to having to underline everything and make sure there are hundreds of references that in reality don't matter.
You can't underline truth with a yellow highlighter.