Has old pro Dick seen The Light? There've been sf novels with religious themes before (e.g., Blish's A Case of Conscience, Miller's A Canticle for Leibowitz, Zelazny's Lord of Light), but none as relentlessly theological in tone, texture, and import as this. God ("Yah"), booted off Earth by the Romans, has taken up residence on a remote methane-snow planet. And when squatters from Earth arrive, Yah decides it's time to make a comeback as his own Messiah. So he contacts dome-dweller Herb Asher (who agrees to claim God's paternity); impregnates ailing neighbor Rybys Romney; and journeys to Earth in the latter's womb--a necessary subterfuge, since Earth is controlled by the Belial-inspired Christian-Islamic church and the Scientific Legate, with computer Big Noodle keeping tabs on everyone. Thus reborn on Earth as Emmanuel, Yah is helped by Elias Tate (who's Elijah reincarnated) and by girl-of-mystery Zina (who turns out to be the living embodiment of the Torah) to recover his powers and challenge Belial for the supremacy. With profuse, muddled plotting in the Dick manner--though without any of the usual Dick playfulness--this is destined, perhaps, to be pored over in seminaries; but it's far, far too heavy to attract many mainstream sf readers.