Working through Isaiah’s repeated declarations that “I am the LORD, and there is no other,” the sermon shows how God makes Himself known to His people – as their Redeemer who formed them, calls them by name, and promises “do not fear, for I am with you.” This self-revelation is the ground for Israel’s confidence even in exile, since the same LORD who created light and darkness also raised up Cyrus to fulfill His word.
The sermon then moves to the Ten Commandments, where God introduces Himself the same way – “I am the LORD your God, who brought you out of the land of Egypt” – as the reason His people owe Him exclusive worship and obedience. It closes on the New Testament’s picture of “one Lord, one faith, one baptism,” showing the same God at the center of both Testaments.