(Isn't that what the forthcoming resurrection of the dead clearly presents?)
...we have the testimony of the martyr Saint Stephen, the creation story in Genesis...
Luke doesn't say in Acts 7 that Stephen saw the glory of Jesus and the glory of the Father. It says Stephen saw Jesus at the right hand of the glory of God.
IoW, God's eminating presence was visible...says NOTHING at all about a "body"...
As for the creation story, yes, God said, "Let us make man in OUR image." a plurality-in-unity: Adam and Eve were indeed a plurality-in-unity who immediately BECAME "ONE FLESH" (Gen. 2:24).
Besides, if Adam was made in God's literal bodily image, are you claiming that ALL of womankind is excluded from being made in God's image?
.. do you believe that the “oneness” is in purpose and perfection/completeness or are they a single being? I don’t find that the single being jives with the Bible.
#1: He is One Essence/Nature -- yet is three Persons
#2: He is so unified 'He' is a 'He' -- vs. a 'Them': "...He, -- while existing alone -- yet existed in plurality." (Hippolytus, 205 AD -- about 175 years after Christ died)
When Jesus said in John 10, that "I and my Father ARE one"...both Hippolytus (205 AD) and Tertullian (213 AD) made a big emphasis that the "are" there is "plural":
* "He did not say, 'I and my Father AM one', but ARE one. For the word 'are' is not said of one person." (Hippolytus)
* "...'I and my Father are one.' ... This is an indication of two Beings -- I and my Father. Furtheremore, there is the plural verb, are,'... (Tertullian)
Clement of Alexandria, in 195 A.D., pointed out how time is one...yet "eternity...presents in an instant the future, the present, and also the past of time." Eternity itself represents a derivative of God's 3-in-1 nature.
Also, you need to read all of Acts 7. It doesn't say what you said it says: http://biblehub.com/acts/7-55.htm
But Stephen, full of the Holy Spirit, looked up to heaven and saw the glory of God, and Jesus standing at the right hand of God.
Check out Acts 7:56 for even more clarification:
and said, "Behold, I see the heavens opened, and the Son of Man standing at the right hand of God!"
Spirits don't have right and left sides, do they? Wait, before you dig the hole deeper by saying it's just figurative see Rev. 3:21. Don't even start on the "it's an honorific" track.
http://biblehub.com/interlinear/revelation/3-21.htm
That also hits the full heirship part that Christians can expect.
Clement's spot on about eternity. You can imagine becoming eternal, then you too will have no beginning, right?
You'll need to be more specific about what is or isn't the Trinity. Your exposition doesn't clarify anything, really.
How about a mathematical proof:
A. Heavenly Father = Jesus Christ = the Holy Ghost
or
B. Heavenly Father ≠ Jesus Christ ≠ the Holy Ghost
or
C. It's a mystery.
Pick one.