2 Cor. 13:14
"The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit, be with you all." - ASV.
Does that verse really say the Father, the Son, and the holy spirit are three persons who constitute the one Most High God? Doesn't it say, instead, that the Lord Jesus Christ is one individual, the holy spirit is another individual (whether a person or a thing), and that God is another different individual?
Does it say Jesus is God? Does it say the holy spirit is God? No, it treats God as someone entirely separate from those two! So, either the inspired Bible writer is completely ignoring the person of the Father: "the grace of...Christ [an individual person]...the love of [a composite] God...and the communion of the spirit [an individual person or thing], or, since the Father alone really is the only true God (Jn 17:1, 3; 1 Cor. 8:6), Paul is including the person of the Father in this verse and properly identifying him alone as God (as all his readers at that time well knew).
We might also look at the "three-in-one" aspects of 1 John 5:8. It would be best to use most modern Bible translations here since the King James Version has been proven to have spurious material added at 1 John 5:7 (even most trinitarian scholars freely admit this). - See http://examiningthetrinity.blogspot.com/2009/08/1-john-57-kjv.html
If Matt. 28:19 adds up to three things being equally one God, then 1 John 5:8, which includes the Spirit, is a much more certain proof of a three-in-one God! There's only one slight problem: the two other "persons" who are equally one with the Spirit have unexpected "names"! -
"For there are three who bear witness [this is the only place in the entire Bible we find a 'trinitarian' formula that even mentions the word 'three'!], The Spirit [which is God according to trinitarians], and the water, and the blood: and the three [are] in one." - ASV.
This is by far the clearest "trinitarian" statement in the entire Bible!! It is the only one that even mentions "three" (although we could work in other numbers like "seven" at Rev. 4:5 or "four" at Rev. 4:6 which has 4 living creatures "in the midst of" God's throne, we can't find any use of 'three'). And to top it all off it says "the three are in one." (The ASV renders "agree in one," but the word "agree" is not really found in the Bible manuscripts here. It literally says "the three are in one." - Compare the MLB: "the three are one.")
And who are these three equal "persons" (who bear witness) who are equally the holy spirit (since the three are all "in one"), who, according to trinitarians, is God? Why these three "persons" who are equally God are the Spirit, the water, and the blood! (Notice how verse 9 also shows that these three are "really" God: the witness of these three is really the witness of God!)
Of course an honest, clear statement of a trinity would be:
"For there are three persons who compose the only true God: The Father, the Son, and the Holy Spirit. And these three persons are the One God."
You see, it isn't a difficult statement for anyone to write, let alone an inspired Bible writer. Even "God is three (treis, masculine)" would be honest, clear evidence at least, but you will never see even that in the inspired scriptures.
Therefore, this clearest of trinitarian "proofs" (1 John 5:8) shows "conclusively" that if the Holy Spirit is God, His two equal partners are not Jesus and Jehovah, but the "persons" of "the Holy Water" [of baptism] and "the Holy Blood" [of the Messiah's sacrifice]!