God who is the self Existent, how He must need be the three Persons. All the three Persons are one and the same self Existent. The second Person is both God and *not God, not God in that He alone on behalf of being God does everything God does. All the temporal actions as God, create, speak appear. John 1:3. The third Person is how they are the one and the same God, John 4:24. This simple is not simple. It is in plain evidence in the NT. Tradition calls this it a mystery, but Trinity is the name of the explanation.
* As someone other than God, "with God," John 1:2.
* YHWH, God the Father. Proverbs 21:30.
* The Word, the Logos, the uncaused Cause, the Son of God. John 1:3.
* The Holy Spirit, one essence how all three Persons are one essence. John 4:24. Romans 8:9, Romans 8:16. 1 John 5:10. 1 Corinthians 2:16.