'O God' in the Bible

"You are my witnesses," declares the LORD, "and my servant whom I have chosen, so that you may know and trust me and understand that I am the One. Before me no God was formed, nor will there be one after me.

This is what the LORD says, the King of Israel and its Redeemer the LORD of the Heavenly Armies is his name "I am the first and I am the last, and apart from me there is no God.

I am the LORD, and there is no other besides me: and there are no gods. I'm strengthening you, although you have not acknowledged me,

"Truly you are a God who hides himself, O God of Israel, the Savior.

They seek me day after day, and are eager to know my ways, as if they were a nation that practices righteousness and has not forsaken the justice of their God. "They ask me to reveal just decisions; they are eager to draw near to God.