Although it was the first to be written, author Blish classed his A Case of Conscience as the third of a trilogy. It is the third in terms of chronological setting, although the three do not have a continuous plot, and the mid-21st-century A Case of Conscience could not, in fact, follow after the events described in the 20th-century Devil’s Day. The three books of the trilogy are joined by theme, rather than plot. They each enigmatically address the question of whether “secular knowledge” leads inevitably toward supernatural evil.
As a piece of thoughtful Golden Age science fiction, A Case of Conscience includes what now stands as an alternate history for the second half of the 20th century. Blish projected a “shelter economy” in which the threat of nuclear war drove all the wealthier countries literally underground, creating an economically committed but psycho-socially unsustainable troglodyte civilization composed of city-states under a UN aegis.
But the core dilemma of the book has to do with humanity’s first contact with an alien intelligence. FTL interstellar travel has been recently invented, and the exoplanet of Lithia has been found to harbor a race of intelligent bipedal reptiloids with utopian social and material harmony, and no god-notions at all. The principal characters of the novel are the four members of the first exploratory team to Lithia, to which is added the Lithian Egtverchi, brought back to Earth as an egg. More than half of the narrative centers on the Jesuit exo-biologist Ramon Ruiz-Sanchez.
There are two plot arcs in the book, with the first taking place on Lithia, and the second on Earth. The Lithian part–culminating in the joint decision of the exploratory team regarding future human relations with Lithia–was originally a stand-alone short story, and many reviewers seem to prefer it, and to be uncomfortable with the transition to the second arc. The second part is to Heinlein’s Stranger in a Strange Land as King Kong is to Tarzan.
The most artful feature of the novel is an ending that ties both plot arcs together, and justifies the supernaturalist dogmas of the Jesuit father without violating the materialist presuppositions of the other characters. Ultimately, though, no matter how sympathetically drawn Ruiz-Sanchez might be, I found his intricately stabilized doctrines to be unsound, and ludicrously based on an unwarranted privileging of humanity, to say nothing of their wrongheaded affirmation of what Jan Assman calls the Mosaic distinction, elevated this time to the far reaches of outer space.