still older than christianity..
i mean, plotinus was the guy who travelled to persia, then came up the trinitarian concept...which influenced st augustine who himself was instrumental in formulating the trinitarian doctrine.
the '3' was never in question...it was more about understanding how they relate to each other..
Brahman
Vishnu
Brahma-Shiva
Brahma-Shiva are the causal level...eg creation and dissolution. ~The first and the last. our spiritual descent and ascent.
The holy spirit, the First and the last.
The spirit of God hovered over the waters...
the waters being the universal consciousness..the logos. The Holy Spirit gives the morning star eg wisdom. Wisdom was the first thing created.
If they are written in the 2nd century, then no. Apostles Thomas and Bartholomew were present in Parthia and India already in the first half of the 1st century AD.
With regards to your Trimurti, where does Brahman fit into this? The Trimurti is a tritheistic concept of three devas. Devas in Hinduism are the elemental (material) powers of the universe. They are not transcendental. They are the Indian equivalents of other polytheistic pantheons, whether Semitic, Greek, Norse, ... If you want to find similarity in Hinduism with Christian teaching, one should look in the Upanishads. The Brahman-Atman is reminiscent, possibly identical, to the concepts of the outer and inner, the Christ and inner Christ in Christianity. But in Hinduism I haven't yet come across an equivalent of the Christian trinity. Its predecessor is nowhere to be found in Hinduism according to me, but in Zoroastrianism. Zarathustra is the one who gave the devas their proper place as lesser (and evil) deities and founded the first true monotheism. He lamented the ritual sacrifices of the sacrificial priests who keep the righteous from the "Best Thought", just as Jesus did with the Pharisees in the Temple of Solomon:
Gatha 32
11. It is they, the liars, who destroy life, who are mightily determined to deprive matron and master of the enjoyment of their heritage, in that they would prevent the righteous, O Mazda, from the Best Thought.
12. Since they by their lore would pervert men from the best doing, Mazda uttered evil against them, who destroy the life of the Ox with shouts of joy, by whom Grehma and his tribe are preferred to the Right and the Karapan and the lordship of them that seek after the Lie.
In Zarathustra's Hymns you actually find the exact equivalent of the later Christian Trinity:
Gatha 28
1. With outspread hands in petition for that help, O Mazda, I will pray for the works of the holy spirit, O thou the Right, whereby I may please the will of Good Thought and the Ox-Soul.
2. I who would serve you, O Mazda Ahura and Vohu Mano, do ye give through Asha the blessings of both worlds, the bodily and that of the Spirit, which set the faithful in felicity.
3. I who would praise ye as never before, Right and Good Thought and Mazda Ahura, and those for whom Piety makes an imperishable Dominion to grow; come ye to me help at my call.
---> Vohu Mana, meaning the Good Thought. Equivalent of the Holy Spirit.
---> Ahura Mazda, meaning Divine Wisdom. Ahura (literally: Lord), masculin word. Mazda, feminine word, is the equivalent of the Graeco-Christian Sophia (Wisdom). Together they form one, Father-Mother, as in the Christian Gnostic system. Just as the union of Father-Mother (Sophia) produces the Son (Logos), so too does the union of Ahura and Mazda produce Asha (literally: the Word).
---> Asha, or Asha Vahishta (literally: True Word), in the Gathas commonly translated as Right (Christian equivalent = Truth). is the Son of Ahura Mazda / Father-Mother, ie. the Logos
One could thus literally rephrase the first three verses of Gatha 28 as follows:
1. With outspread hands in petition for that help, O Sophia, I will pray for the works of the holy spirit, O thou the Son, whereby I may please the will of Holy Spirit and the Ox-Soul.
2. I who would serve you, O Mother-Father and Holy Spirit, do ye give through The Son the blessings of both worlds, the bodily and that of the Spirit, which set the faithful in felicity.
3. I who would praise ye as never before, the Son and the Holy Spirit and the Father-Mother, and those for whom Piety makes an imperishable Dominion to grow; come ye to me help at my call.
The Trinity is right there. For some reason this goes unnoticed. But Zarathustra reformed Vedism, the trinity is not Vedic or Brahmanic. Plotinus met with Persian philosophers, Zoroastrians. But the Greek and Persian philosophers had already had contact before Christ. Their encounters most likely fertilized the soils of the Hellenized world to receive God's Word. Thomas and Bartholomew had already gone to the Persians in 43AD. The Gnostic scriptures (eg. Secret Book of John) already contained the Trinity before Plotinus.
He said to me,
“John, why doubt?
Why be afraid?
Don’t you know this image?
Be not afraid.
I am with you (plural) always.
I am the Father
The Mother
The Son
I am the incorruptible
Purity.
- Secret Book of John
Zarathustra basically turned the Hindu cults on their head, just like Christ did with the henotheistic cults of the Semites. But Zarathustra didn't claim to be the Messiah. He prophesied the incarnation of Asha:
Gatha 43
15. As the holy one I recognized thee, Mazda Ahura (Father-Mother), when Good Thought (Holy Spirit) came to me, when the best Tushna-Matay taught me to declare: "Let not men seek again and again to please the Liars, for they make all the righteous enemies."
16. And Zarathushtra himself, O Ahura (Lord), chooses each one of thy holiest Spirit, O Mazda. May Right (the Logos) be embodied full of life and strength!
"be embodied" = receive a body.
Zarathustra prophesied the Saviour:
Gatha 44
1. This I ask Thee, tell me truly, Ahura - as to prayer, how it should be to one of you. O Mazda Ahura, might one like thee teach to a friend such as I am, and through friendly Right give us support, that Good Thought may come to us. (through friendly Word give us support, that the Holy Spirit may come to us.)
2. This I ask Thee, tell me truly, Ahura - whether at the beginning of the Best Existence the recompenses shall bring blessedness to him that meets with them. Surely he, O Right, the holy one, who watches in his spirit the transgression of all, if himself the benefactor of all that lives, O Mazda. (He, O Word, the holy one, who watches in his spirit the transgression of all, if himself the Benefactor (literally: Gr. Iesous Chrestos = "the Good Saviour" / Avestan: Saoshyant = "one who brings benefit" or Astvatereta = "he who embodies truth") of all that lives.)
The Christians had a
Gospel of Zostrianos (teachings of Zoroaster) which says the following Christian teaching:
"Know those who are alive and the holy seed of Seth. Do not [show] disobedience to me. [Awaken] your divine part to God, and as for your sinless elect soul, strengthen it. Behold death here and seek the immutable ingenerateness, the [Father] of everything. He invites you, while they reprove you. Although they ill-treat you, he will not abandon you.
Do not baptize yourselves with death nor entrust yourselves to those who are inferior to you instead of to those who are better. Flee from the madness and the bondage of femaleness and choose for yourselves the salvation of maleness. You have not come to suffer; rather, you have come to escape your bondage.
Release yourselves, and that which has bound you will be dissolved. Save yourselves so that your soul may be saved. The kind Father has sent you the Savior and given you strength.
Now we may understand who the biblical Magi from the East were, and why they brought with them myrrh, gold and frankincense to the birth of Jesus. They are ceremonial items still used by Zoroastrian clergy today.
To wrap this up, when you say the Gita are a superior teaching than the Gospels, I'd say this:
Christ is the culmination of every inspired prophecy that came before it, whether the precedents were of divine inspiration or acquired higher wisdoms through philosophy and meditation, it was all achieved by men who extended their hand to God. With Christ, it was God Himself who extended His hand to us.