Next Second Isaiah has Yahweh proclaim to all the nations that he is the only God. Yahweh wanted all the survivors of the various nations to assemble and come together. They were stupid, since they carry around their wooden idols. They pray to these wooden idols that cannot save them. Let them make their case and counsel together. Who was able to tell about things long ago before they actually happened? Only Yahweh was able to do that. There is no other god besides Yahweh, who is a righteous God who saves. Yahweh defends himself against all these other gods.
In the strongest possible personal terms, first person singular, Yahweh proclaims that he alone is God. There is no other god. Yahweh claims that the Israelites are his witnesses, since they are his servant that he has chosen. Clearly, this servant is the Israelites. They know and believe in the Lord. They understand who he is. There was no other god before Yahweh and there will be none after him. There is no other savior who can deliver the Israelites, so that no one can hinder him. There were no strange gods among the Israelites. Once again, the Israelites are the witnesses for Yahweh. Yahweh is truly God.