An absolute and inescapable divine judgment is destined to sweep through the world, bringing about profound spiritual change and the eradication of evil. God issues a final, decisive decree [אבן עזרא, מצודת ציון]. Although divine decrees can bring either blessing or hardship, this specific judgment is one of severe punishment [שד״ל]. The destruction is meant to be total and complete [רד״ק], ensuring that only a small remnant of the vast population survives [מצודת דוד].
This severe measure carries a clear spiritual purpose. When humanity witnesses God executing justice upon the wicked, they will be humbled, ultimately submitting to Him and repenting of their ways [רש״י]. The scope of this decree is global, playing out across the world through the military campaigns of Sennacherib, who is destined to conquer numerous kingdoms [שד״ל].
Yet, even though the decree of destruction is sealed, the outcome takes a dramatic turn for the people of Israel. God chooses to redirect the calamity toward the idol-worshipping nations that blaspheme Him, causing them to suffer the punishment in place of Israel. Because of this divine mercy, Israel is saved, and the inhabitants of Zion have no reason to fear Sennacherib's advancing armies [מלבי״ם, שד״ל].