The last half of Isaiah 9 is in the form of a prophetic poem consisting of four stanzas, each one ending with the sentence: “For all of this His anger is not turned away, but His hand is stretched out still.”
The words are directed to the Northern Kingdom of Israel, not Judah. They had been warned about the coming judgment on their sin numerous times. This prophetic poem speaks of the unrelenting anger of God against the sin of his people. It also speaks of the unrelenting love of God, “for whom the Lord loves, he disciplines.”
This is an oxymoron to us: How can God display His grace through His judgement? In Isaiah 9:8 through 11:16 God reveals his gracious intentions toward Israel, the Northern Kingdom. Though His wrath works against them in the Assyrian invasion, God promises to punish Assyria for its arrogance and promises to give his purified people a home in the messianic kingdom.
Each of the four stanzas has a slightly different emphasis.