This poem sounds like a creepy, druidic chant. Think Stonehenge, fire, candles, darkness, and people in cloaks and hoods, chanting this poem in really deep voices. Not only does the rhythm and rhyme scheme contribute to the chant quality, but the parallelism (the repetitive usage) of the grammatical structures in the questions enhances the pulsing beat.
Not only that, but the phrases become shorter and shorter through the fourth stanza, which seems to speed the reader along or raise his voice into a crescendo! If you get a classroom full of students reading this poem aloud, the classroom next door will probably get chills thinking about the strange rituals going on in first-period English. These religious undertones were surely not unintentional, and, along with the Christian images and allusions, contribute to the visionary quality of the poem.