Can you tell me what scriptures support the concept of the Trinity?

Dear Gramps,
I have been trying to convince a protestant friend of mine about our belief in the godhead as being three separate beings.  I have quoted to him from Genesis, “let “US” make man in “OUR” image….” for which I state to him that these beings are speaking as plural, not one.  Can you tell me the scriptures that they use that their trinity is one in all three?
Fred, from Cheraw, South Carolina

Dear Fred,
I don’t have any idea what scriptures the churches use who believe that the Father, the Son and the Holy Ghost are three manifestations of one God. The concept of the Trinity was not formalized until the Council of Nicea in 325 AD. There are no scriptures that I know of that promote this concept. However, there are many that may be easily interpreted as referring to three distinct individuals in the Godhead, and that Jesus Christ and God the Father are indeed two separate beings. As examples—
Matthew records at the baptism of Jesus—

And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased (Matt  3:16-17).

If, during the baptism of Jesus, the voice of the Father was heard from heaven, they could not have been but one person. And the Spirit of God was also present descending from heaven.
In John  8:13-18, we read—

The Pharisees therefore said unto him, Thou bearest record of thyself; thy record is not true. Jesus answered and said unto them, Though I bear record of myself, yet my record is true: for I know whence I came, and whither I go; but ye cannot tell whence I come, and whither I go. Ye judge after the flesh; I judge no man. And yet if I judge, my judgment is true: for I am not alone, but I and the Father that sent me. It is also written in your law, that the testimony of two men is true. I am one that bear witness of myself, and the Father that sent me beareth witness of me.

This passage cannot be interpreted as the Father and the Son being two expressions of the same being, as the Savior is explaining that they are two persons in the same sense that according to Jewish law the truth must be established by two separate witnesses. The Savior cites himself as one witness and his Father in Heaven as a second witness. Had the Savior taken himself to be one manifestation and his Father another manifestation of the same being, he could never have used such an analogy to satisfy for the Pharisees conformity with the Jewish law requiring two witnesses.
Again, from the mount of transfiguration, we hear the Father’s voice from heaven in the presence of the Savior declaring to Peter, James and John—

This is my beloved Son, in whom I am well pleased; hear ye him (Matt  17:1-5).

And as a final proof that the Godhead comprises more than one distinct person, in our own time, on a spring morning in the year 1820 both the Father and the Son appeared in person to the young boy, Joseph Smith, as he sought the Lord in prayer to ask which of all the churches were true. He reported—

When the light rested upon me I saw two Personages, whose brightness and glory defy all description, standing above me in the air. One of them spake unto me, calling me by name and said, pointing to the other–This is My Beloved Son. Hear Him! (JS-H  1:17)

Gramps