I don't at all care if a thread is "derailed," unless an issue is being deliberately ignored. We disagree perhaps because we don't agree on your priority list.You may have heard of this "jar of life" analogy - you have a large jar, first you put in rocks, plenty of empty space left; then you slip in pebbels, there's still space; then you fill the remaining gaps with sand to volume, and it's finally full. However, if you change the order by putting in pebbles or sand first, there'll be no room for rocks. This is a famous demonstration to teach time management and priorities, but it also applies in a lot of other areas including the primary, secondary and tertiaru issues in Christianity. Primary issues are the essential beliefs, the core narrative of the bible - creation, desecration (or fall), redemption and glorification, that is the narrative of our life that shapes our worldview through which we perceive all the information input from the world, and that sets us apart from the world; secondary issues are denominational differences in practices and traditions, while tertiary issues are theologies and doctrines. The way I see it, trinity belongs to the third category, and this statement alone will upset a lot of folks who insist that trinity is the foundation of Christianity instead of those four pillars I named, they identify themselves as "trinitatian" first before a child of God and play identity politics against others, that's how they get hostile. And if you're obsessed with the "sand" that is these theological positions and stances, you won't have any mental capacity for the "pebbles" and "rocks" that really matter. Sorry for this rant, I don't mean to derail this thread, just to explain why trinity topic should be banned.
I wouldn't at all put "doctrines" in the last and 3rd group. Doctrine is the bulwark of the Christian faith. Among doctrines I would put Trinitarianism as a high priority--perhaps not the highest. I should think that Salvation through Christ is number one, along with living in Christ.
But Trinitarianism is very important because our Salvation is contingent upon our faith in Christ. For this kind of faith to be viable Christ needs to be seen as Savior, Lord, and God.
Hence, the Trinity. God the Father and God the Son. I do understand that some sects have had trouble with the Spirit as a Person in the Trinity, but that does not detract from essential Trinitarianism, which sees the Father as God and the Son as equally God.
I would clearly put denominationalism last because often that is simply dependent upon the society you grew up in. If you grew up in Scandinavia or Germany you might be a Lutheran. If you grew up in the UK you might be Anglican, Methodist, or Presbyterian.
What is much more essential when considering denominations is whether the church you attend is conservative or spiritual, spiritual or purely nominal? Sometimes a large denomination may be very weak, but individual churches within that denomination solid and valuable.
But you seem to distinguish between "essential beliefs" and "doctrine." I don't see where the dividing line is except with your personal consideration of what is more valuable to you?
The battle over the Trinity was one of the 1st major theological battles in Christian history. There is a reason for this. Those who took the wrong side in this often ended up in heresy-land.
One heresy leads to another, and heretics ended up in full-blown pagan philosophy of one sort or another. It was important to maintain certain tenets to keep things on track with your "primaries."
Just my opinion....