'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 believe MeAnd understand that I am He.Before Me there was no God formed,And there will be none after Me.

“Thus says the Lord, the King of Israel and his Redeemer, the Lord of hosts:‘I am the first and I am the last,And there is no God besides Me.

“I am the Lord, and there is no other;Besides Me there is no God.I will gird you, though you have not known Me;

Truly, You are a God who hides Himself,O God of Israel, Savior!