The speaker is busy, distracted, and in the middle of that, demands an answer, as if placing an order. What they want is not a gentle or thoughtful reply but one "full of ring and rage": loud, forceful, and cold. The wish is strikingly large. They want an answer that could "stop all future worlds from being," which suggests a need for a conclusion so final that nothing else could follow from it.
The ending is quietly unsettling. The speaker says there will be "no doubt in any part of me after a while." That "after a while" matters. Certainty isn't instant here; it seems to be something the speaker expects to settle in, perhaps by force of will. The poem suggests that conviction can be manufactured rather than discovered, and that it comes at a cost: closing off every other possibility. The mood is tense, hard, and a little chilling, like a door being shut with great finality.