Isaiah promised that those who wait on the Lord will renew their strength (40:31). But what will take their strength? How will God renew it (41:1)?
Assyria would attack Israel in 701 B.C., which Isaiah foretold of about a decade earlier. Babylon would later invade Israel towards the end of Isaiah’s life (39:6-7). Finally, the Chaldean flavor of Babylon would finish off Israel, destroying Jerusalem in 587 B.C.
But God is God; He writes every script (41:25-26). He disciplines His people through Babylon, and He will justly judge Babylon. Two centuries before the events would happen, God through Isaiah predicts both the final destruction, and His people’s redemption. He will call another “servant,” a Persian ruler, who will overthrow the Chaldean Babylonians. Then this “servant” will allow His people to return to their homeland, exactly when Isaiah predicted He would. He is accurately called by name later in 44:28 - Cyrus.
Thus Israel will “renew their strength,” but not because they are inherently special - God calls “Jacob” (Israel) a “worm” twice in this chapter. It is only because God is utterly gracious, always keeping His promise to His friend, Abraham (41:8). So then, regardless of what His people face tomorrow, they need not be controlled by fear (41:10). Look past your circumstances, O people of God, to who your God is. Then, seeing Him, cast off your worthless idols (21-29; 1 Cor. 14). He glorifies Himself by providing for us (17-21).