John Calvin Commentary Isaiah 52:6

"Therefore my people shall know my name: therefore [they shall know] in that day that I am he that doth speak; behold, it is I." — Isaiah 52:6 (ASV)

Therefore shall my people know. In this verse, He concludes what He had alluded to in the two preceding verses: that eventually the people must be redeemed by God, who cannot be inconsistent with His own nature. For, if He redeemed the fathers, if He always assisted the Church, their posterity, whom He has adopted in the same manner, will never be allowed by Him to be overwhelmed.

We should carefully observe the word “know,” for to “know the name of the Lord” is to lay aside every false opinion, and to know Him from His word, which is His true image, and next from His works. We must not imagine God according to human imagination, but must understand Him as He reveals Himself to us.

The Lord, therefore, concludes that He will indeed assist them and will fulfill all that He has promised, so that the people may know that their hope has not been without foundation, and that they may be more and more confirmed in the knowledge of His name. We must remember what we have said elsewhere about experiential knowledge, which confirms the truth of the word.

That it is I who speak. The verb “to speak” relates to the promises. הנני (hinni, Behold I,) relates to actual power, as if He had said, “Although now there is nothing more than the words sounding in your ears by which I promise what seems unlikely, yet you will quickly obtain it, for I will indeed accomplish what I promise.” From this, we should draw the universal doctrine that the promises of God and their fulfillment are linked together by an indissoluble bond. Whenever, therefore, Satan tempts and urges us to distrust, as if God had forsaken and abandoned us, we must come back to this point and place our confidence in God, who never promises anything in vain. “Even if He has not yet fulfilled it, He will still assist in due time.”