Genesis 1 gives us the seed of the Triune God and God builds upon this throughout the milleniums.
I am not a member of the Roman church, but human politics in Rome does cause many problems with that particular church as power became more important than God.
God spoke to God when the person of the Son was on earth and the person of the Father was in heaven. The theory of modalism cannot be accurate. Yeshua said we should baptize in the name of the Father, the Son and the Holy Spirit. One being, three persons. It oozes through scripture, but you deny it.
This non plural name is "Jesus" who is the full Godhead bodily, his is the Name for those titles, he is called the eternal father, he could say "in the name of the Father and the Son and the Holy Spirit" because he was the Godhead bodily. If he would have said "in my name and in my Fathers name and the Holy Spirits name" then we would have plural names. I wont consider the "Stop in the name of love" "of law" argument because that might be a more recent term that wasnt around back then, im not using it.
As for man other than Jesus, they all must say in HIS name. This oozes well too.
Acts 2:38
Acts 10:48
Acts 8:12
Acts 8:16
Acts 19:5
Acts 22:16
1 Corinthians 6:11
Here is some interesting versus as well.
The LORD possessed me in the beginning of his way, before his works of old. I was set up from everlasting, from the beginning, or ever the earth was. When there were no depths, I was brought forth; when there were no fountains abounding with water. Before the mountains were settled, before the hills was I brought forth: While as yet he had not made the earth, nor the fields, nor the highest part of the dust of the world. When he prepared the heavens, I was there: when he set a compass upon the face of the depth: When he established the clouds above: when he strengthened the fountains of the deep: When he gave to the sea his decree, that the waters should not pass his commandment: when he appointed the foundations of the earth: Then I was by him, as one brought up with him: and I was daily his delight, rejoicing always before him; Rejoicing in the habitable part of his earth; and my delights were with the sons of men.
Proverbs 8:22-31
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In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by him; and without him was not any thing made that was made.
John 1:1-3
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Ye are my witnesses, saith the LORD, and my servant whom I have chosen: that ye may know and believe me, and understand that I am he: before me there was no God formed, neither shall there be after me. I, even I, am the LORD; and beside me there is no saviour. I have declared, and have saved, and I have shewed, when there was no strange god among you: therefore ye are my witnesses, saith the LORD, that I am God. Yea, before the day was I am he; and there is none that can deliver out of my hand: I will work, and who shall let it?
Isaiah 43:10-13
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That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life; (For the life was manifested, and we have seen it, and bear witness, and shew unto you that eternal life, which was with the Father, and was manifested unto us
1 John 1:1-2