Since this is a pick for my book group, I'm not going to go into so much detail as usual. But this has been a thought-provoking read, since I am a fan of the movie Blade Runner and yet had never read the novel on which it was based. A lot of the holes in the movie have been plugged by the novel, and yet the story in the novel is decidedly different than that in the movie.
One of the elements missing from the movie is the near-religion, Mercerism. Wilbur Mercer is a perhaps legendary figure in the setting of the novel, one who apparently had the ability to raise animals from the dead. The background of the novel involves a nuclear war and the effects of the fallout on the people who remain on Earth. It's also clear that the fallout has decimated the animal population, such that animals are luxury items, even spiders. Mercer's ability to resuscitate them is a fairly obvious symbol for hope. But the legend goes on to say that authorities burned the resuscitation power out of him with cobalt, tossing him into what is described as a "tomb world" from which he continually strives to arise. His attempts take the form of climbing a large hill, whereupon he is pelted by rocks from an unseen assailant. For some reason, Mercer never seems to complete his journey up the hill.
"Worshipping" Mercer is a peculiar activity. Households are equipped with Mercer boxes, display screens with handles whose images are unfathomable until the handles are grasped. When the viewer does this, the screen becomes clear and a state of empathy with all other viewers currently grasping their Mercer boxes is achieved. Together they experience Mercer's long climb up the hill and feel his pain when he is pelted by rocks.
The parallels to Christianity are apparent. Given the purely mechanical nature of the source of empathy for the Mercerists, I wonder if Dick was making a sly commentary on Christians, implying that their own empathy is missing outside of Christian influences—if they weren't Christian, they would be sons of bitches. A slightly different interpretation leads to Dick implying that Christians only feel empathy with other Christians, and then only within the church. Both of these are hypercritical assertions, made more accurate by the last 20 years of fundamentalist rebirth, where many people loudly proclaiming their Christianity show little or no patience with people outside their own belief system (in a sort of irony that those types may not get, they often call themselves "evangelical" which literally means "sharing good tidings" which is the opposite of what these people do). I suppose Dick's observation does not have to focus on Christianity, but on the all-too-human capacity to share warmth and empathy with those that are similar to us, rather than those who are different than us.
Which in turn plays along nicely with one of the movements of the book (And movie)—how to tell the difference between humans and human creations designed to look and act convincingly human. Most stories regarding androids (Dick's term, rather than "replicants" that the movie uses) being hunted are told from the android's point of view. Dick instead tells his story mostly from the point of view of the hunter, Rick Deckard, and his confusion and questions that arise from a realization that perhaps these creatures aren't so different after all, and in fact humanity sometimes shows just as much empathy as the androids. A secondary character that provides a point of view for the story, John Isidore—a "special" whose intelligence has been adversely affected by radiation and fallout—experiences this confusion as well as he hides the last three androids from Deckard's hunt. He is puzzled by the androids's actions, and then when he meets Deckard, he is similarly confused by his apparent insensitivity to his friends and their fate. Isidore can't know that nothing could be further from the truth, that Deckard feels he must assert his humanity by destroying the androids or, as Mercer tells Deckard, doing bad things is sometimes necessary.
Again, the parallel with fundamentalist belief systems is powerful. Fundamentalists of one religion crash airplanes into skyscrapers for what they perceive to be the greater good. Fundamentalists of another religion bomb abortion clinics in order to protest the taking of life. And while Dick is renowned for the paranoia that runs through his writing, his fear seems well-founded in this regard.