To arguments from windy books
He makes an answer plain,
And see how gay his plumage looks
Despite the pouring rain.
Your main critique of my faith is freshman-level stuff ("windy books") using language like "truth claims" and "proof" which are completely out of place discussing ancient texts -- there is my plain answer. The whole stanza has an English-weather theme with its rain and wind, within the overall conceit of armed combat ("sword", "shield") where the "plumage" would refer both to a literal plume or crest on the helmet, and to my manner of dress and toilet which you mock relentlessly and which I defiantly maintain. There is the gratuitous use of "gay", also a double meaning, though playfully vapid.
I would rather draw your attention to the "urn" in the final stanza which here signifies both mortality and aesthetics, after Keats, an allusion I expected you to grasp immediately. It is a figure of which I am very proud.
My reason for recycling the poem is just to demonstrate that, early on in our fight over Christianity, I called my shot. This is a metaphor from what you call snooker, and is generally held to be a feat and a sign of mastery.