Three short lines carry a surprising amount here. The speaker goes to church, a place we expect to be about community, ritual, or faith, but says that what they really made there was a home "in a book." The sentence is hard to pin down: the book might be a Bible or hymnal, or it might be something else entirely that the speaker read while sitting in the pew. The poem doesn't say, and that openness is part of its charm.
The title helps. "Bibliolator" means someone who worships books, so the speaker seems to love the written word almost as a religion of its own. Church becomes less a place of prayer than a shelter for reading. There's a quiet, gently humorous edge to this, as if the speaker slipped away from the service without leaving the room.
The mood is calm, private, and a little wry. Nothing is stated loudly. The feeling is of someone absorbed, comfortable, and content to live among pages.