'O God' in the Bible

“You are My witnesses”—this is the Lord’s declaration—“and My servant whom I have chosen,so that you may know and believe Meand understand that I am He.No god was formed before Me,and there will be none after Me.

This is what the Lord, the King of Israel and its Redeemer, the Lord of Hosts, says:I am the first and I am the last.There is no God but Me.

I am Yahweh, and there is no other;there is no God but Me.I will strengthen you,though you do not know Me,