Who invented idea of the Trinity Doctrine?

The Trinity doctrine began its slow development over a period of centuries. 

The trinitarian ideas of Greek philosophers such as Plato, who lived several centuries before Christ, gradually crept into church teachings. 

Before Plato, triads, or trinities, were common in Babylon and Egypt. 

And the efforts of churchmen to attract unbelievers in the Roman world led to the gradual incorporation of some of those ideas into Christianity. 

This eventually led to acceptance of the belief that the Son and the holy spirit were equal to the Father. 

So, what is the Trinity doctrine? It is actually a pagan doctrine masquerading as a Christian one. 

It was promoted by Satan to deceive people, to make God confusing and mysterious to them. 

This results in their also being more willing to accept other false religious ideas and wrong practices.

The Trinity wasn't "invented." It was revealed. Like formal education, God doesn't reveal everything all at once but a little at a time to give man a chance to absorb it.

“The impression could arise that the Trinitarian dogma is in the last analysis a late 4th-century invention. In a sense, this is true . . . The formulation ‘one God in three Persons’ was not solidly established, certainly not fully assimilated into Christian life and its profession of faith, prior to the end of the 4th century.”​—New Catholic Encyclopedia (1967), Volume 14, page 299.

“The Council of Nicaea met on May 20, 325 [C.E.]. Constantine himself presided, actively guiding the discussions, and personally proposed . . . the crucial formula expressing the relation of Christ to God in the creed issued by the council, ‘of one substance with the Father.’ . . . Overawed by the emperor, the bishops, with two exceptions only, signed the creed, many of them much against their inclination.”​—Encyclopædia Britannica (1970), Volume 6, page 386.

GOD HAS ALWAYS BEEN THREE IN ONE....IN GENESIS IT CLEARLY SAYS "WE" MAKE MAN IN "OUR" IMAGE.

The doctrine that God is three divine persons emerged from existing Christian beliefs, and very quickly -- though not quickly enough for a *name* for the doctrine to come into use.

The Jews knew of God, primarily the Father. Yet there were hints even in Judaism that God was not simply alone. 

"Let us make man..." "Let us go down and confuse their tongues.." The story of the visit to Abraham by three men/angels who are also called the LORD is another event that's just "back there" in the consciousness. In fact, the icon of the visit to Abraham is the primary icon of the Holy Trinity, in Orthodox practice. David's words are also interesting about the Messiah, whom David calls "Lord". Yet the Messiah is also known to be David's descendant. This we necognize as the Word of God incarnate, Jesus Christ, God in human flesh.

Among early Christians, the Holy Spirit was also known to be God, as when Ananias and Sapphira lied to God by lying to the Holy Spirit. 

It took a while to actually have to articulate the teaching. The Father is God. The Word is God. The Spirit is God. Neither is the other. Yet there is one God. This we still believe, and now have a name -- the Holy Trinity.

The Trinity is of God himself.

GOD HIMSELF HAS STATED IT MANY TIMES STARTING WITH IN THE BEGINNING GOD SAID, "LET US MAKE MAN IN "OUR" IMAGE"!!!

SEE HERE FROM THE HOLY BIBLE>>>
JESUS IS GOD, SEE HERE WHERE HE TELLS US MANY TIMES IN THE BIBLE FIRST WHERE HE TELLS PHILLIP HE IS GOD,>>>>

 Philip said, 'Lord, show us the Father and then we shall be satisfied.' Jesus said to him,

9 'Have I been with you all this time, Philip, and you still do not know me? 'Anyone who has seen me has seen the Father, so how can you say, "Show us the Father"?

10 Do you not believe that I am in the Father and the Father is in me? What I say to you I do not speak of my own accord: it is the Father, living in me, who is doing his works.

11 You must believe me when I say that I am in the Father and the Father is in me; or at least believe it on the evidence of these works.

EXPLANATION OF JESUS SAYING ONLY THE FATHER IS GOOD>>>

I know at glance it seems like Jesus is questioning why they call Him good. However, He is agreeing that He is good, but bringing to their attention that this goodness is from the Father and the good they see in Him is because He is light from light, true God from true God.

He was saying that if people recognize that He is good then they should know that He is God. They should recognize that God is the source of goodness, not man. He was raising people's minds to recognize the Messiah.

ALSO, THIS IS PROOF GOD IS A BLESSED TRINITY IN GODS OWN WORDS JESUS TELLS YOU HE IS GOD MANY TIMES, ALSO THE TRINITY IS IN THE SAME BIBLE, GOD SAID, "LET US" MAKE MAN IN "OUR" IMAGE, AND WHEN GOD AT THE TOWER OF BABEL, GOD SAID, let "us" go down and confuse their language so they will not understand each other! HENCE HIS TWO MESSAGES THAT GOD IS THE BLESSED TRINITY

BELOW ARE DIFFERENT TIMES JESUS SAYS HE IS "I AM" GOD.

JESUS TOLD THE PHARISEES WHEN THEY SAID TO JESUS, DO YOU PUT YOURSELF ABOVE ABRAHAM AND JESUS SAID, BEFORE ABRAHAM, "I AM" MEANING HE IS GOD

WHEN MOSES ASKED GOD HIS NAME, GOD SAID HIS NAME WAS "I AM"

OTHER TIMES JESUS SAID, "I AM" THE DOOR TO HEAVEN.

"I AM" THE WAY, THE TRUTH AND THE LIFE

"I AM THE VINE, YOU ARE THE BRANCH'S

JOHN 17:5 And now glorify thou me, O Father, with thyself, with the glory which I had, before the world was, with thee.


John 8:58
Jesus said to them: Amen, amen I say to you, before Abraham was made, I am.

saias (Isaiah) 43:10
You are my witnesses, saith the Lord, and my servant whom I have chosen: that you may know, and believe me, and understand that I myself am. Before me there was no God formed, and after me there shall be none.

https://www.ewtn.com/faith/teachings/incaa3.htm

I WILL GIVE YOU TWO EXAMPLES THEN MORE IN MY LINK. FIRST THE BIBLE IS GOD'S WORD AND THE WORD BECAME FLESH(JESUS, GOD, MAN) AND DWELT AMONG US. SECOND, WHEN SATAN TEMPTED JESUS, JESUS SAID, YOU SHALL NOT PUT THE LORD YOUR GOD TO THE TEST. ALSO READ JOHN 14: 1 THRU 12

As a concept, 'the Trinity' can be traced as far back as the ancient Sanskrit word 'trimurti' (or "Three forms of God).  The Vedic/Hindu faiths of India, credited with the founding of the world's great religions, portrayed God as the "three divine characters", Lords Shiva (the Supreme Creator/Destroyer), Vishnu (The Supreme Personality), and Brahma (The Absolute).

It's not uncommon for ancient religions to depict God as a Divine Trinity of some sort.  The ancient African faiths featured the Trinity of Assur, Asset and Heru, which the Greeks adopted as Osiris, Isis and Horace.  Similarly, the Zoroastrian faith divides God into multiple parts, such as Apam Napat, Mithra and Ahura Mazda.  Judaism is an exception that doesn't accept God as a Trinity, which is why we don't see the word appear in the Bible; coming from the Jewish/Hebrew faith and culture.

Since the Council of Nicaea recognized God as 'Transcendent and Immanent', is makes sense to portray 'One God', made of multiple traits.  The innumerable gods, goddesses, demi-gods, etc., of the Vedic/Hindu faiths make up the 'Supreme God' of the universe, in the same way the various spirits of nature make up the 'Great Spirit' in the Native American faiths.  

The "Father, Son and Holy Spirit", are the 'different' (not "separate") aspects of the same 'Supreme Infinite Godhead', out of which all things arise.  The Trinity would signify the Divine Attribute of 'Omnipresence', expressed as 'Creator', 'Created', and 'Creation', which are fundamental to all of existence.  God is a Trinity in the same way that 'H2O is still water', whether as a "liquid solid, or vapor", and even all three at once, as in the "triple-point" state.  

Trinity-deniers, typically accept God as omnipresent, but maintain that He cannot exist as, "Three Persons", in 'One'; while we recognize many things existing as multiple things at once.  The human mind and intellect cannot comprehend or conceive of the 'Enormity and Magnitude of Divinity', yet, we reduce God into the mind's familiar sense of "form", to gain some semblance of meaning and understanding.

The material world of form, is dominated by the "law of threes" to maintain cosmic balance and harmony.  Since the ideas of "monism and dualism" imply each other and cancels out, a "third aspect" is necessary so that one extreme does not completely dominate it's polar opposite.  God being the most 'Universal Being' there is, trinities of all sorts can be found inherently in the natural occurring world.

All the atoms of the universe is an accumulation of "protons, electrons and neutrons".  Light has been discovered to travel as "a beam, particles and waves".  The core material elements consists of "water, earth and gases".  The concept of finite time, as in "past, present, and future", comes from our perception's linear observation of 'sequential change', as material form passes through "beginning, middle and end".

Even the human condition is described as a triune of "mind/body/spirit", experienced in the "third-dimensional" realm of existence.  The Catholic Church was established on many traditions and customs that come from other faiths, and accepts the Trinity Doctrine as 'spiritual fact'; which isn't any different from religions sharing the concept of an 'afterlife' as a post-mortal existence.  

It's not uncommon for followers of the Vedic/Hindu faiths to accept Jesus Christ as an 'Avatara' ("Divinity Incarnate").  Lord Krishna (the Jesus-figure of the Bhagavad Gita), said, "I am Vishnu", who is comparable to the 'Son' of the Holy Trinity.  Lord Krishna's name means "All Attractive" in Sanskrit, which the Greeks translated to 'Kristos', later becoming 'Christ' (or 'Anointed') in Aramaic, the language Jesus spoke.  

The modern Roman Catholic Church is a schism from the original Catholic Church (now usually called Orthodox), from which it broke away nearly ten centuries ago over whether the Roman branch could revise the common Creed without consulting the others. 
 
That Creed dates from the fourth century and represents the formal affirmation of the doctrine of the Trinity. The doctrine itself is not so much invented as inherited, from the very early days of Christianity. What had to be invented in the fourth century was an explanation of how the Trinity could possibly be. 
 
From at least the early second century, if not earlier, Christians generally believed that 
-- the Father, of whom Jesus preached, is God; 
-- the Holy Spirit, of whom Jesus also preached, is God; and 
-- the Son, a title Jesus used for himself, is God, God living a human life. 
These were sometimes referred to as a triad. 
 
In the early fourth century, a priest named Arius was publishing devotional poetry that became popular. And it was plain from the poems that Arius considered the Son, at least, to be a DIFFERENT god and subordinate god from the Father. But many Christian leaders had learned their ideas about God as passed down from Jewish sources, and Judaism emphasized belief in just one God. 
 
That had to be sorted out, especially as a new Roman Emperor had just ended his predecessors' persecution of Christians and made them a favored religious group. This Emperor Constantine, like any good Roman general, expected them to get their organization straight. So he ordered a Council of Christian leaders, who affirmed one more principle: 
-- Christians believe in just one God. 
 
It took a few decades for some philosophically-oriented Christian leaders to explain this clearly. They distinguished between the divine Being, the one God, and the three divine Persons. Each of the Persons was that one Being, yet each was distinct from the others. The explanation is practically mathematical in its clarity. 
 
It sometimes confuses people who are used to the usual situation, where each person is a separate being. But God is the creator of all personhood, and God is not subject to purely human limits. So while it is not our usual way of seeing the concept, it is not at all illogical. 
 
Roman Catholicism inherits the concept from the Orthodox churches among which it used to exist. And we Protestants inherit the concept from Roman Catholicism. 

Jesus, the Ever Living Christ