Shared ground
These verses explain the motive behind the violent imagery of the surrounding scene (63:1–3): the speaker says he acted because a “day of vengeance” was already set in his heart, and the “year” to reclaim “my redeemed” had arrived. That pairs judgment on enemies with rescue for a particular people (explicit textual claims).
The speaker also stresses complete independence: he looked for help and found none, and no one “upheld” him. So “my own arm” brought deliverance, and his wrath/anger “sustained” him (explicit textual claims). The action is then described as trampling “the peoples,” making them stagger like the drunk, and pouring their lifeblood on the ground (explicit textual claims, with vivid imagery).
Where interpretation differs
How literal are “day” and “year”? Some read them as a concrete moment and a defined period in history; others take them as symbolic time markers that signal “now is the appointed time” without specifying a calendar date.
Who are “my redeemed” in this context? Some take this as the speaker’s own covenant people in a direct, immediate sense (Judah/Israel in crisis). Others think the phrase can also be read more broadly as all whom God claims as his, with the immediate historical situation as the starting point.
Who are “the peoples”? Some read this as particular hostile nations (with Edom prominent in the larger scene), while others read it as enemies in general—any power opposing God and threatening his people.
What does “my own arm” mean? Many take “arm” as a metaphor for power and decisive action; others think the solitary, warrior-like presentation invites readers to picture a more concrete champion figure, while still recognizing the phrase functions as a way of saying the victory was God’s alone.
Why the disagreement exists
The passage uses time-words (“day/year”) and group-words (“redeemed/peoples”) that can naturally be read either narrowly (specific events and nations) or more generally (a pattern of judgment and rescue). It also uses intense poetic imagery (trampling, drunken staggering, blood poured out) that raises the question of how much is descriptive detail versus picture-language meant to convey total defeat.
What this passage clearly contributes
The text presents judgment and rescue as linked: the same act that is vengeance toward “the peoples” is deliverance for “my redeemed.” It also highlights divine self-sufficiency: no human ally or supporting force is credited; the speaker’s “own arm” accomplishes the outcome, and wrath is portrayed as the driving energy that “upheld” him. Finally, it shows how Isaiah can describe reversal of humiliation in deliberately public, graphic terms to emphasize the completeness of the victory (compare the larger scene in Isaiah 63:1).