A Hugo-winner from near the end of Blish's most creatively fertile decade, A Case of Conscience does not, in this humble reader's opinion, stand up to the test of time. I'll grant you there is much fine writing here, and for its day, the novel deals with the weighty issues of religion, science, and personal responsibility with much sensitivity and intelligence. Yet as a story it's a pretty patchwork affair that buries its fine ideas under mounds and mounds of talk and doesn't seem sure, ultimately, of what its message really ought to be.
Told in two parts, the first and much superior of the two was published as early as 1953 as a novella. It focuses on Father Ramon Ruiz-Sanchez, a Jesuit priest who also happens to be a biologist on a four-man team investigating the planet Lithia. Lithia has given rise to a species of intelligent lizard-beings, who have developed a purely rational culture in which everyone pretty much goes about his business, and there is no war, crime, or dissent. There is also no religion. The Lithians seem to be patently incapable of religious faith. For Ruiz-Sanchez, this is a paradox. Convinced, as are many Christians, of the fallacy that ethics and morality without religion are impossible, Ruiz-Sanchez is at a loss to explain this planet, which he likens to the Garden of Eden before original sin came along. Is it possible that original sin simply never happened on Lithia, or could there be another explanation?
Ruiz-Sanchez makes up his mind what that explanation must be: rather than admit that perhaps his beliefs may well be groundless, he makes the astonishing conclusion that Lithia must have been created by Satan to test the faith of Christians! As such it must be quarantined forever. This is the recommendation he makes to his team when they meet to discuss whether or not they should recommend opening up the planet to travel from Earth. It's insane on the face of it, but what makes this part of the book so remarkable is that Blish has Ruiz-Sanchez argue his maniacal position quite well...though not quite well enough that its fallacies and bogus assumptions weren't obvious to your good old friendly neighborhood atheist like me. Nevertheless, I enjoyed this section of the book the most; it's rare when an SF author incorporates religious themes into a novel in a manner that isn't just a simplistic excuse to either proselytize or mock faith. (None of the biographical pages I have found for Blish on the web has had any info about the man's own religious convictions, if any.) It's rarer still when the end result is so craftily told that I feel the urge to leap into the pages and debate with the characters!
Anyway, Ruiz-Sanchez's decision is troubling to him because it is heretical: Satan cannot create, only God. Upon his return to Earth, a Lithian whom he has befriended gives Ruiz-Sanchez an urn containing the embryo of its own offspring.
At this point the story moves into its considerably more problematic second half. The infant Lithian, Egtverchi, grows up on an Earth obsessed with war paranoia (remember the publication date, folks; much of this book has Cold War written all over it) and governed by a "Shelter" society wherein most of the world's inhabitants have taken to living underground. Egtverchi becomes first a celebrity, then a loose cannon in this world; he fails to see any logic in the way humans live their lives, and yet, not having grown up in the Lithian culture, he hasn't been socialized into their peaceful and pragmatic ways of thinking either. So he becomes the ultimate rebel, refusing to conform to any of Earth's laws, and, through his highly popular television show (yes, we've gone from theological debate to satire in less than 100 pages), encouraging all of the disaffected and downtrodden of Earth to do the same. Chaos ensues, blah blah blah.
This second half of the novel simply hasn't got the focus of the first. In the first half, the story centered squarely on Ruiz-Sanchez and his inner personal turmoil over his beliefs and his responsibilities both to those beliefs and the people back on Earth whom he represents. Responsibility is one of the themes of the novel's second half, too, but Blish frantically darts his attention back and forth between several characters. In addition to both Ruiz-Sanchez and Egtverchi, there are Michelis and Liu, Egtverchi's adoptive human parents. Egtverchi's slide into completely antisocial mania isn't well supported dramatically; there aren't any sequences which show the character's arc from good guy to bad guy convincingly. In fact, the alien is something of an asshole from the minute we first see him.
By trying to cover too much ground as the book nears its finale, Blish tries his readers' patience and the whole affair leaves you with no one to root for, and no particular desire to hang out in this insane, bleak, and chaotic world. But that first half is some truly brilliant, classic storytelling that showed Blish, when in his prime, could have easily been a Grand Master. The decline of his career into Star Trek novelizations and early death at 59 seem doubly sad. Read the first half sometime if you have an afternoon to kill, but be aware that in its second, this Case of Conscience is little more than a case of nuts.