Fear not, neither be afraid: have not I told you from that time, and have declared it? you are even my witnesses. Is there a God besides me? yea, there is no God; I know not any.
Read Chapter 44
Cyril of Alexandria
AD 444
Having made mention of the knowledge in Christ, recapping things for our benefit, he now turns his address to something else that is very necessary. For at the time when the godly prophet Isaiah composed the words about such things, offensive and irresistible temptations ruled over them. For what “God” and “honor” meant seemed to be up to the judgment of each individual. So God needs to provide them with some rousing encouragement and arguments tailored to their situation. He turns them away from polytheism and the sicknesses that troubled them and summons them through a change of mind to a knowledge of the truth and of his glory and brings them back to the awareness of his incomparable power. - "Commentary on Isaiah 4.2.44.6–7"
Witnesses. The history of the true religion is its best proof, chap. xliii. 9, 10.
Known. Ruled, consequently no other can be truly God. (Calmet)
Idolaters are foolish, trusting in those who cannot announce future events. (Worthington)
Who is like me? Let him call the things that are not as if they are and let him explain the order of my creation, by which reason I have set humans free in motion as I made them on the earth. And this is not all I will to do, but I also seek out for them knowledge of things to come. So you, Israel, whose king and redeemer I am, do not fear idols, which you have learned on Mount Sinai to be nothing. - "Commentary on Isaiah 12.18"