The reason that I’m bringing this novel up in a forum where religion lurks in the background is that Miéville explicitly brings religion into his story. It may be impossible to explain precisely how he does this without the detailed summary that I’ve already begged off giving, but it is nevertheless noteworthy that in any sufficiently complex world religion emerges. We tend to think that religion is something that evolved from the slime and now that we’ve bathed in the light of pure reason it will eventually be washed into the gutter of discarded concepts. History demonstrates repeatedly that such is not the case. Religion is resilient and, dare I say it, inevitable. Human beings—perhaps also other conscious beings—know that there is something outside ourselves. That’s the foot in the door for higher beings or forces or worlds. In a word, religions.
Fiction writers frequently appeal to religions for verisimilitude. Are imaginary worlds believable without religions? It’s a long stretch. Star Wars has characters calling belief in the force a religion. Star Trek, in any number of episodes, dealt with gods. Anathem was based on the monastic ideal. Science fiction has trouble when it leaves religion completely out of the picture. A non-deistic universe is nearly incomprehensible to the human mind. Even great scientists and other rationalists occasionally lapse into thoughts about luck, fate, or fortune. Embassytown doesn’t focus on religion throughout, of course. It may be a minor subplot. But translating an alien world with a language that can’t be understood into a fiction of English is facilitated by putting a religion into the general mix. This is a smart and complex world, but when you read it you’ll find it believable because a religion naturally emerges. And that, I say, is realism.