The Trinity Says that God is 1 being with 3 distinct consciousness and it is found in the Bible itself:
Bible says God is 1 being/essence/substance
For you are great and do wondrous things; you alone are God.
1 Chronicles 17:20
“O LORD, there is none like You, nor is there any God besides You, according to all that we have heard with our ears.
1 Corinthians 8:4
Therefore concerning the eating of things sacrificed to idols, we know that there is no such thing as an idol in the world, and that there is no God but one.
‘See now that I, I am He, And there is no god besides Me; It is I who put to death and give life I have wounded and it is I who heal, And there is no one who can deliver from My hand.
Bible says God has 3 distinct minds/persons/consciousness
“For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.
And he who searches hearts knows what is the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God.
In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God.
And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.
When Jesus had spoken these words, he lifted up his eyes to heaven, and said, “Father, the hour has come; glorify your Son that the Son may glorify you,
And now, Father, glorify me in your own presence with the glory that I had with you before the world existed.
And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; and behold, a voice from heaven said, “This is my beloved Son, with whom I am well pleased.”
Go therefore and make disciples of all nations, baptizing them in the name(singular) of the Father and of the Son and of the Holy Spirit(plural, 3),