When his football team was in hopeless disarray, Vince Lombardi took them back to the first fundamental: ​”Gentlemen, this is a foootball…”  When God’s people were in hopeless disarray, He did the same.  

He said, [I want you to] “…know and believe me and understand that I am he. Before me no god was formed, nor will there be one after me. I, even I, am the Lord, and apart from me there is no savior.”   (Isaiah 43:10b-11)

That’s the foundation.  Start there or nothing else will make sense.  And yet, people commonly refer to “my god,” as distinguished from “your god.” The real God is the only God, from eternity to eternity.

He is One.