'O God' in the Bible

And he said unto him, Thus says the LORD, Since you have sent messengers to inquire of Baal-zebub the god of Ekron, is it because there is no God in Israel to inquire of his word? therefore you shall not come down off that bed on which you are gone up, but shall surely die.

And he returned to the man of God, he and all his company, and came, and stood before him: and he said, Behold, now I know that there is no God in all the earth, but in Israel: now therefore, I pray you, take a blessing from your servant.

And have cast their gods into the fire: for they were no gods, but the work of men's hands, wood and stone: therefore they have destroyed them.