Mainline Christian denominations believe that the Father, Son and Holy Spirit are the only Deity.
Don't know if you believe this. But Mormons do not.
The First Council of Nicaea defined the Trinity as being three persons (hypostases) with one essence (ousia).
Origen, (c. 182 – c. 251) used it when he said God is one genus of ousia yet three distinct species of hypostasis: namely the Father, the Son, and the Holy Spirit.
The Synods of Antioch in 264-268 condemned the term homoousios (same substance) because of its Greek language and philosopher roots. The Catholic Encyclopedia article on Paul of Samosata states:
It must be regarded as certain that the council which condemned Paul rejected the term homoousios; but naturally only in a false sense used by Paul; not, it seems because he meant by it an unity of Hypostasis in the Trinity (so St. Hilary), but because he intended by it a common substance out of which both Father and Son proceeded, or which it divided between them, — so St. Basil and St. Athanasius; but the question is not clear. The objectors to the Nicene doctrine in the fourth century made copious use of this disapproval of the Nicene word by a famous council.
The First Council of Nicaea in 325 debated the terms homoousios and homoiousios. The word homoousios means “same substance”, whereas the word homoiousios means “similar substance”. The council affirmed the Father, Son, and Holy Spirit (Godhead) are of the homoousious (same substance). Many commentators—most notably Walter Gibbon—have noted that the entire controversy hung on a difference of the smallest Greek letter (i, or iota).
The Chalcedonian Creed of 451 stated God is one ousia yet three hypostases.
Perhaps the description of the Trinity by St. Patrick’s concept of the Trinity, using a 3-leaved clover to highlight the Christian belief of ‘three divine persons in the one God’ as opposed to the widely held (at the time)Arian concept which regarded the Son of God, the Logos, as a created being.
(Trinity)
And neither did the early Christians - and Jesus never said it - He did, however, say: "“Is it not written in your law, I said, Ye are gods? If he called them gods, unto whom the word of God came (and the scripture cannot be broken), say ye of him, whom the Father sanctified and sent into the world, Thou blasphemest; because I said, I am the Son of God?” (Jno. 10:34-36).
Jesus is the First Born Son, The Word, the Logos for our world =
There are many who believe that God the Father is the Supreme Creator of the Universe, that He sent His First Born Son, Jesus, to us = to teach us The Way back...and before Jesus left us, He promised to send 'another' - the Holy Spirit, the Still Small Voice that would testify to truth to us, to be our Comforter, His messenger, as it were.
Many do not believe in man's later interpretations that purport God the Father, His First Born Son, Jesus and the Holy Spirit to one entity = One in thought, one in deeds, yes - as we should be. But not one entity - it doesn't make sense to some that, if Jesus was also God the Father, He would pray to himself, for example, in the Garden, to have "This cup" removed from Him - but 'nevertheless' accepted the Father's decision, whichever way it went.
Many can't understand why one would claim that Jesus and the Father were the same entity and then when He was baptized, He would come down in the form of a dove and say, "This is My Beloved Son..." of Himself?
Jesus didn't teach the trinity. He said "I and the Father are One" "He who has seen me has seen the Father" = etc - Many take this in the manner of speaking of the time - to mean, I and the Father are one and who has seem me... means, we are one in thought, in deeds, in precepts...that Jesus, as God's living representative on earth, whatever He said/did was in complete harmony with the Father = and He came to teach us to know and do the same...as our heritage.
He told the disciples, before He left, in answer to their question about what they should do, how to carry on, without Him.
He told them that "Those things, which ye have both learned, and received, and heard, and seen in me, do: and the God of peace shall be with you. Philippians 4:9"
Indeed, He told them that they could not only do everything they had see Him do = which was His purpose here, to teach us how to do the Father's work, but that they would be able to do even more, as they would still be here to carry on after He was gone....
The point is: There are many different interpretations of the scriptures. All man can do is follow the Light as he understands it while searching for more understanding - there is no time left over to spend on tearing others down -= and NO ONE of us on this planet has the power to interpret for God or condemn our fellow man.
That's the Father's domain. Sufficient unto the day are our own responsibilities in our personal lives.
http://www.bibleanswer.com/uaregods.htm
May His Peace be unto you