Romans 8:15, “For you did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons, by whom we cry, ‘Abba! Father!'”
Perhaps the most significant thing you can say about the one true and living God is that He is the Father of His people. Michael Reeves says “the most foundational thing in God is not some abstract quality, but the fact that he is Father.” The label Father is not limited to the New Testament, where Jesus so often spoke of our Father in heaven; it appears throughout the Old Testament as well. Even before God was seen as the Creator of the heavens and the earth, He was the God the Father — alongside Jesus the Son of God, and God the Holy Spirit.
Consider a few OT verses (esv) about the Fatherhood of God…
Exodus 4:22, “Then you shall say to Pharaoh, ‘Thus says the LORD, Israel is my firstborn son…”
Deut. 32:6, “Do you thus repay the LORD, you foolish and senseless people? Is not he your father, who created you, who made you and established you?”
Isaiah 63:8, “For you are our Father, though Abraham does not know us, and Israel does not acknowledge us; you, O LORD, are our Father, our Redeemer from of old is your name.”
Isaiah 64:8, “But now, O LORD, you are our Father; we are the clay, and you are our potter; we are all the work of your hand.”