The speaker admits they don't belong in the "church of mathematics," a striking phrase that treats numbers and proof as a kind of religion, with its own rules and believers. Saying "an ill fit" is both a confession and a quiet kind of pride: they would rather stand outside than conform.
The last two lines turn into a challenge. "Show me what is lost by doubt," the speaker says, as if no one has ever proved that being unsure costs us anything. Then comes the odd, lovely image of "a long-desired night." Night suggests darkness, mystery, and things we can't measure, yet here it's something wished for, not feared. Judging by the title, the poem sets certainty against that kind of open, uncertain experience.
The mood is calm, defiant, and a little playful. The speaker isn't angry at logic, just unwilling to treat it as the only source of truth. In only four lines, the poem makes a case for wonder and not-knowing.