'O God' in the Bible

Then the angel of Yahweh spoke to Elijah the Tishbite, "Get up, go up to meet the messengers of the king of Samaria and speak to them, 'Is it because there is no God in Israel that you [are] going to inquire of Baal-Zebub, the god of Ekron?'

Then they said to him, "A man came up to meet us, and he said to us, 'Go, return to the king who sent you and speak to him, "Thus says Yahweh, 'Is it because there is no God in Israel that you [are] sending to inquire of Baal-Zebub the god of Ekron? Therefore the bed upon which you have gone, you will not come down from it, for you will surely die.'" '"

and he said to him, "Thus says Yahweh, 'Because you have sent messengers to inquire of Baal-Zebub, the god of Ekron--is it because there is no God in Israel [from whom] to inquire his word?--therefore the bed upon which you went, you shall not come down from it, for you shall surely die.'"

When he returned to the man of God, he and all of his army, he came and stood before him and said, "Please now, I know that there is no God in all of the world except in Israel. So then, please take a gift from your servant."