Please note: God's name appears around 6800 times in the Hebrew Bible (The Old Testament). It is represented by four Hebrew words.
Therefore, in these lessons, God's name will be represented as YHWH.
God is Always One, Never Three or Three-in-One
Thousands upon thousands of singular personal pronouns are used to describe God. It is not an assumption, but a fact that the Bible presents God as a singular person. Furthermore, Jesus says that the greatest commandment is to understand that God is "one Lord" and to love him (Mark 12:29). Nowhere does any Scripture attest that God is three, three-in-one, or anything more than a simple one.
Deuteronomy 4:35
"YHWH, He is God; there is no other besides Him."
"See now that I, I am He, And there is no god besides Me."
Deuteronomy 6:4
"Hear, O’ Israel, YHWH is our God, YHWH is one."
Isaiah 46:9
"I am God, and there is no other; I am God, and there is no one like Me."
Nehemiah 9:6
"You alone are YHWH…"
Malachi 2:10
"Do we not all have one Father? Has not one God created us?"
Mark 12:29
"And Jesus answered him, The first of all the commandments is, “Hear, O Israel; YHWH our God is one Lord.”
John 5:44
“…you do not seek the glory that is from the one and only God.”
Romans 3:30
"… Since indeed God is one."
1 Corinthians 8:6
"…for us there is but one God, the Father."
Galatians 3:20
"Now a mediator is not for one party only; whereas God is only one."
"You believe that God is one. You do well; the demons also believe, and shudder."
The above post is based on an article taken from here.