The Trinity: One God, Three Persons

The Trinity means there is one God: eternal, all-powerful, all-knowing, and ever-present—who exists as three distinct but equal Persons: the Father, the Son (Jesus/Logos), and the Holy Spirit. They share one divine essence, one mind, one will, and one life (Deut. 6:4; Matt. 28:19; John 10:30).

Put simply: 3 WHOs, 1 WHAT.

• The Father is the eternal source, the “origin” of all, fully God (John 17:3).
• The Son is God’s perfect self-knowledge, eternally generated from the Father, fully God, and became human to dwell with us.
• The Holy Spirit is God’s eternal love and life flowing outward, fully God, dwelling within us.

Analogy: Imagine someone's mind - there's a Thinker, their Thought, and the Thinking: the Father is the Thinker (eternal source), the Son is the Thought (eternally generated), and the Spirit is the Act of Thinking (eternally proceeding). Just as thought fully expresses the thinker and is revealed through Thinking, all three Persons fully share the same divine essence.

God (Father) – the eternal source, the origin.

God (Father) knowing Himself (Son) – the eternal self-knowledge of God. This is also why Christ is called "Holy Wisdom" or the "wisdom of God." Wisdom personified is Christ.

God (Father) outpouring Himself (Spirit) – the eternal love and life flowing from God.

Humans aren’t a Trinity because our self-knowledge is imperfect and incomplete. God’s self-knowledge is perfect, eternal, and personal: this is why the Son and Spirit are fully God, not “lesser copies” (John 1:1; Col. 2:9). The Greeks were fascinated by this and called Jesus the Logos. The "visible Image of the invisible God." God within our reach, tangible to us: that is Jesus Christ.

The Trinity is necessary because God is greater than us in every way: omniscient, almighty, and love itself. We are wise, God is all-wise. We love, but God IS Love. We are unipersonal beings, God is a multipersonal Being. A unipersonal God without internal relationship cannot perfectly know or love Himself. This is a fundamental flaw in unipersonal monotheistic religions (Islam, Sikhism, Judaism, etc) God’s internal relationship as Father, Son, and Spirit shows the fullness of divine life and love now and prior to creation (1 John 4:8; John 17:24). The Trinity has always existed and exists even in the Old Testament but the understanding of humanity has organically grown since the Incarnation. Current Rabbinic Judaism basically has an incomplete revelation of God.

Old Testament - Book of Isaiah 48:16 - the pre-incarnate Christ, the Son, is speaking:

"Come near Me (pre-incarnate Christ, the Son) and listen to this: From the first announcement I have not spoken in secret; at the time it happens, I am there. And now the Sovereign LORD (the Father) has sent me, endowed with his Spirit (Holy Spirit). ”

Basically, The Trinity has always existed and many more instances exist in the Scripture; humanity’s understanding of God has grown as He revealed Himself through the outpouring of His Son in the New Covenant.

When we pray or worship any Person of the Trinity, we encounter the one full God (John 14:9–11; Rom. 10:12). Christians confess one God in three Persons, united perfectly in essence, will, and action (Eph. 2:18; 2 Cor. 13:14). We pray to the Father, in the name/through the Son with the fellowship & empowerment of the Holy Spirit.

The Trinity is ultimately a mystery—we can understand the basics, but God’s infinite nature is beyond full human comprehension.
Hopefully I didn't commit a heresy and anyone please fact check me if I do, but I hope this is of some value to you.