Charles Ellicott Commentary Isaiah 45:4

"For Jacob my servant`s sake, and Israel my chosen, I have called thee by thy name: I have surnamed thee, though thou hast not known me." — Isaiah 45:4 (ASV)

For Jacob my servant ... —The words “servant” and “elect” show that the prophet speaks of the ideal Israel, the true Ecclesia, rather than of the nation as such outwardly, though this also, as including the other, shared in the outward blessings of the election. Essentially, the words declare that the world’s history is ordered with a view to the true Ecclesia.

Called you by your name. —Either as predicting the actual name of Koresh, or as giving the titles of “Messiah” and “shepherd.” This descriptive title clearly refers to these.

Though you have not known me. —Better, when you did not know me, either as referring to a time prior to the recognition by Cyrus of Jehovah as the God of heaven (Ezra 1:1–2), or, possibly, prior to his birth (Jeremiah 1:5).