The Trinity of Christendom, as defined in the creed of Nicea, is a merging of three distinct entities into one single entity, while remaining three distinct entities.
Christians must regard the three gods as one god because they are co-eternal, co-substantial and co-equal, though only the second had a life of his own!
This Neo-Platonic doctrine is pagan not Jewish and, since the Jewish scriptures form part of the Christian bible, it is heretical (Isaiah 43:10) to imagine the Trinity as three separate gods. This mumbo-jumbo arises clearly and precisely because the first bishops opportunistically tried to merge Judaism with paganism. Most ancient religions were built upon some sort of threefold distinction. Deities were always Trinities of some kind or consisted of successive emanation in threes.
The oldest and probably the original form of the Trinity is that found in Indian religion. Classical Hinduism dates back to at least 500BC, with roots extending as far back as 2000BC. The Hindus had a doctrine of the divine Trinity called Tri-murti ( Three-forms) consisting of Brahma, Vishnu, and Siva: Brahma, the Father or supreme God, Vishnu, the incarnate Word and Creator, and Siva, the Spirit of God, the Holy Spirit or Ghost. It is an inseparable unity though three in form. Worshippers are told to worship them as one deity.
In one of the Hindu bibles, (the Puranas) more than two thousand years ago, a devotee is addressing the Trinity of gods, Brahma, Vishnu, and Siva. He says he recognised only one God and asks the Three Lords which is the true divinity that he might address to him alone his vows and adorations. The three Gods, Brahma, Vishnu, and Siva, becoming manifest to him, replied,
Learn, O devotee, that there is no real distinction between us. What to you appears such is only by semblance. The single being appears under three forms by the acts of creation, preservation and destruction, but he is one.
Such concepts posed no problem to Hindu worshippers since they were used to worshipping curious gods. Ganesh had the body of a man and the head of an elephant, Hanuman was a monkey-faced god and other depictions of gods showed them with four, six or eight arms. Gods were strange entities so a god with three aspects was quite simple.
Sir William Jones says:
Very respectable natives have assured me, that one or two missionaries have been absurd enough to in their zeal for the conversion of the Gentiles, to urge that the Hindus were even now almost Christians; because their Brahma, Vishnu, and Mahesa (Siva), were no other than the Christian Trinity.
The Christian fathers almost unanimously proclaimed the Trinity as a leading tenet of the Christian faith and a doctrine directly revealed to them from heaven. Yet a disciple of a pagan religion perhaps two thousand years older than Christianity, defines it precisely. The doctrine of the Trinity was held by Brahmins, Persians, Chaldeans, Chinese, Assyrians, Phoenicians, Scandinavians, Druids, the natives of Siberia, Peruvians, the Indians of meso-America and Greeks long before the council of Nicea of 325 AD officially recognized God's trinitarian nature, and all quite independent of it.
The pagan Romans worshipped a Trinity. An oracle is said to have declared that there was First God, then the Word, and with them the Spirit. Here we see the distinctly enumerated, God, the Logos, and the Holy Spirit or Holy Ghost, in ancient Rome, where the most celebrated temple of this capital
