Three short stanzas, and each one describes eating on a larger scale. First we eat timber, which is odd, since wood isn't food. The poem treats it as something we do almost without choosing, as if "the night proposed it" and we simply agreed. Then comes the line about fish eating fish, with Christ quietly pleased. The speaker seems to be borrowing religious approval for something that is really just hunger and predation.
By the last stanza the appetite has swallowed everything: "we eat the world." The final phrase, "being very full now of God," is a sly twist. Being full could mean satisfied, or stuffed past the point of sense, and filling ourselves with God sounds holy and greedy at once.
The tone is dry and darkly funny. The speaker doesn't scold, and that calm makes the picture more unsettling. The title suggests that consumption has become our whole way of life, and that we've found a way to bless it.