The first thirty-five chapters of Isaiah can be divided into three parts: Chapters 1 – 12; 13 – 27; and 28 – 35. Each of these sections ends with a hymn of praise, and so with a hymn, we come to the end of the first section, chapter 12.
It is not the intent of God to crush His people – at least that’s not the way he describes his actions against them in these first twelve chapters. He’s going to judge them, that’s true. He’s going to discipline them, that’s true. But he does not want to crush their spirit and leave them without hope. And so the Lord has alternated between describing the sins of His people, telling them of the horrors about to befall them because of those sins, and promising a time of redemption and blessing when they have “straightened up” and begun to live correctly. When they finally learn their lesson, they will sing with joy: “Give thanks to the Lord, call on his name; make known among the nations what he has done, and proclaim that his name is exalted.”
When Israel becomes faithful, did you notice who they would praise God to?
Here is one of many references in the Old Testament that underscore the desire of God that His people inform the world about Him. It’s not just a New Testament “Great Commission.” It’s an eternal desire of God, and His expectation of all who claim to be His people.