That is certainly true of the Apostolic Churches and "mainline" Trinitarian Protestants.
However, the problem is what is "core truth". Some will say that all who consider Jesus their Savior believe in "core truth" and therefore represent the Church.
Such all-inclusive generalizations certainly do not define the Church because "Christ" in many of these assemblies is not the same, although they may refer to the Biblical Jesus.
Within a ocuple of centuries the Church found it absolutely necessary to define Who Christ is in order to establish what "core truth" is.
Faced with growing and newly emerging heresies, the Church was forced to define just what Christian "core truths" are. From those proclaiamtions (of the ecumenical Councils) we believe that (1) He is the Hypo-stasis (lit. sub-stance) of the Holy Trinity, one in nature (essence), that is — divine, with the Father and the Spirit; (2) that all Three Hypostases differ in the Divine Economy but are fully equal and indistinguishable in their divinity, one God, indivisible, simple, not compound.
Furthermore we also define that Jesus is the eternal Word of God, Who took on flesh and Human nature and was born of a Virgin; that He is fully God and fully Man; two natures, and two wills, unconfused, in one Person.
These nuances are not obvious from just reading the Bible. Closer scrutiny tells us that the devil is in the details, no pun intended, as some truly satanic cults have arisen from those who call on Jesus as their "savior".
Needless to say, all the various congregations calling on Jesus' name do not share these "core truths".
But what is your conclusion about "subtle nuances"? Are understanding of these required to be Christian?
Yes, most definitely.
I have some slight problem with trying to pin down
CO-EQUAL 100%
In some respects, seems Biblical. In others, not.
Jesus HIMSELF said there was none good except THE FATHER ONLY.
There are some mysteries we just don’t understand fully in our finiteness. And, I don’t think it helps to pretend we do.
Nevertheless, there’s plenty about Biblical truth of the Trinity that I think all Trinitarian Christian groups can feel some significant kinship.
That's a perfectly valid point. Perhaps, with certain exceptions, we could consider it "those truths required for true faith in the true Christ". At service yesterday, our pastor spoke of true faith being "total submission to Christ". Of course, it must be the correct Christ, as you say. However, even with all of our disagreements, I think we actually do agree fully on the identity of Christ. That lets us call each other Christians.
From those proclamations (of the ecumenical Councils) we believe that (1) He is the Hypo-stasis (lit. sub-stance) of the Holy Trinity, one in nature (essence), that is — divine, with the Father and the Spirit; (2) that all Three Hypostases differ in the Divine Economy but are fully equal and indistinguishable in their divinity, one God, indivisible, simple, not compound.
To the extent I understand this, and assuming there are no unobvious entailments, I don't see any problem with this.
Furthermore we also define that Jesus is the eternal Word of God, Who took on flesh and Human nature and was born of a Virgin; that He is fully God and fully Man; two natures, and two wills, unconfused, in one Person.
We're on a roll. :)
These nuances are not obvious from just reading the Bible. Closer scrutiny tells us that the devil is in the details, no pun intended, as some truly satanic cults have arisen from those who call on Jesus as their "savior".
I would agree that not every nuance in the Bible is obvious. But, I would say that they all are discernible from ONLY the Bible by the leading of the Spirit. In addition, from all of those you have listed here, I would say that many ARE fairly obvious from a simple reading.
FK: "But what is your conclusion about "subtle nuances"? Are understanding of these required to be Christian?"
Yes, most definitely.
But if you really believe that, then in your mind only the Orthodox can be Christian. I know you don't believe that. How else would you describe your differences with your closest cousins, whom you obviously consider Christian, but over subtle nuances?