Trinitarian doctrine most definitely does delineate between the Father, Son and the Holy Spirit as three revealed separate "Realities" of one God.
I think the conceptual difficulty with this is that in the West the divine Realities (Hypostases) are called "Persons," and because they are also given (somewhat "paganistic") anthropomorphic names such as Father and Son.
So when you object to the verse by writing 17For (God) received honor and glory from (God) when the voice came to (God) from (God) , saying, "This is (God’s) (God), whom (God) love(s); with (God) (God) is well pleased" and add Doesn’t reading it this way prove the absurdity of your premise – your “Essential/Foundational Christian Doctrine”?
the answer is: the "absurdity" is there but that is because you made it absurd.
You are confusing (and conflating) the "person" with "nature." This is like saying that the mind and the words (and what impact they carry, i.e. the "spirit") that come out of you are not distinct entities of one being but three separate "beings."
You are essentially saying that "the (human) mind is sending the (human) words" and then ask how can 'human' send 'human?' You take God to be the name of a person rather than the name of the Divine Nature.
God simply means divinity. It is a nature, an essence of one being. That being reveals itself (to the Christians) in three recognizable realities which the Christians (unfortunately) call Father Son and Holy Spirit, which leads some to conclude that there are "three gods."
But if you think of it as mind, words and meaning/impact, then you realize that they are not three separate "beings" but three interrelated realities of one being and one nature.
The problem with biblical trinity is that it is subordnationist, which is in part complicated by the dualistic idea of Christ being fully divine and fully human in one and the same being, which also means that divinity and humanity subsist, and that makes it a different conceptual problem.
“No reply”?