Isaiah 45:4-6.”For Jacob My servant’s sake, and Israel Mine elect, I have even called thee by thy name: I have surnamed thee, though thou hast not known Me. I am the Lord, and there is none else, there is no God beside Me: I girded thee, though thou hast not known Me: That they may know from the rising of the sun, and from the west, that there is none beside Me. I am the Lord, and there is none else.”
Jacob and Israel are used here to indicate that ALL Jews, as a nation, are God’s elect, not just part of them. In the Millennium, they will be united under Messiah.
I have surnamed you: That is, by My blessing in making you conquer, you have received the title “Cyrus the Great,” though before this you did not know Me.
Many believe that after God’s call of Cyrus he did know God (44:28; Ezra 1:1-6). It is hard for me to imagine how a man who has been called and used for God’s specific purpose could NOT know that God is real, and that He alone is God.