Show me the verse that uses the term Trinity, or triune. what? Can't find it? I wonder why? Scriptures allude to it but its not spelled out. The terms were defined in 325. They had a general consept and when aspects of it came into question like Was jesus the first created being or was he of like substance they had to define the terms for a fuller better understanding. Note. A full tome of the bible had not been compiled at this time either. Marcion was the first to attempt to do it and excluded regularily accepted books and only include pauls writings while excluding the OT. the Church had to define canon. This is how the church has operated. Now the basics of the faith and the deposit of the Apostles have been the same but specifics were later defined as questions arose. Simple basic history that any history book would tell you.
The simplest and best is 1 John 5:7. Some rail against it, but as I have shown it was referred to prior to 325 AD. Also, since God promised to preserve His word, and I trust He did rather than modern scholars, I believe it. Even if one throws that out, which I don't recommend, there are others.
2 Corinthians 13:14 - "The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all. Amen."
John 5:17 - "My Father worketh hitherto, and I work." John then tells us the Jews sought to kill Him after He said this because He had made Himself equal with God with statement.
John 5:21 - "For as the Father raisieth up the dead, and quickeneth them; even so the Son quickeneth whom he will."
John 10:30 - "I and my Father are one."
John 14:16, 17 - "And I will pray the Father, and he shall give you another Comforter, that he may abide with you forever; Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you."
John 15:26 - But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me."
Matthew 11:27 - "All things are delivered unto me of my Father: and no man knoweth the Son, but the Father; neither knoweth any man teh Father, save the Son, and he to whomsoever the Son will reveal him."
Matthew 28:19 - "Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost."
There are many texts that say something like Grace unto you from God our Father and the Lord Jesus Christ.
1 John 1:1-3 - "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) That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ."
John 1:1-3 - "In the beginning was teh 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 anything made that was made."
I know I'm leaving many other good texts out, but space just will not afford a complete scriptural quotation of all the texts that help frame the great doctrine of the Triune Godhead which are three yet one. Neither can the human mind totally comprehend such an incredible concept, but inasmuch as we today understand it, so too did the early church. The idea that a council in 325 framed these ideas for the first time in Christianity is absurd.
From wikipedia (not always a solid source, but dead on the money here):
"The council did not create the doctrine of the deity of Christ as is sometimes claimed but it did settle to some degree the debate within the early Christian communities regarding the divinity of Christ.
This idea of the divinity of Christ along with the idea of Christ as a messenger from the one God ("The Father") had long existed in various parts of the Roman empire. The divinity of Christ had also been widely endorsed by the Christian community in the otherwise pagan city of Rome.[5] The council affirmed and defined what it believed to be the teachings of the Apostles regarding who Christ is: that Christ is the one true God in deity with the Father. Contrary to the view popularised by Dan Brown's novel The Da Vinci Code, there is no evidence to suggest that the Biblical canon, the list of books decided to be authorative as scripture, was even discussed at the Council of Nicaea, let alone established or edited."