The theme of bringing people back from the dead has been a theme of science fiction and horror at least since the time of Mary Shelley, generally with the underlying moral lesson being that it’s bad bad bad. But as Eve Tushnet notes, the moral argument underlying such a message is often lacking:
most “came back wrong” stories rely on an over-easy assertion that it’s wrong to cheat death without any sense of why that might be true. My most blatant example of this is the Buffy episode right after “The Body”–I can’t remember the title, but if you’ve seen it you know the one I mean–where there’s an explicit conversation about why bringing back the dead might be wrong, but you never get anything beyond, “Uh, it might not work.”
Pet Sematary, I think, actually shows the protagonist’s confusion of love with self-comfort and self-projection from fairly early on in the story–what he wants back is only partly the dead beloved. Mostly he wants to stop hurting–which is incredibly sympathetic… but not quite the same thing. And so it makes sense to me that he gets back nothing but a familiar skin filled with projected horror.
Part of me wants to say that the reason it’s hard to give a justification for the claim that it’s wrong to bring back the dead is because the claim is false. It isn’t wrong to bring back the dead, at least in all circumstances. Christ raised Lazarus, after all. And since it doesn’t seem plausible to say that Mary and Martha had a different psychological reaction to losing a loved one than pretty much everyone else in the history of human kind, the idea that wanting to bring back the dead involves a confusion of love with self-comfort, while it might work well as a literary device, won’t do as a moral argument, I don’t think.
To the extent that there is a principled argument against bringing back the dead, I think it would have to be that doing so was wrong because it would involve “playing God.” God is Lord of life and death, as St. Thomas says, and so any attempt to bring someone back from the dead would seem to involve human beings trespassing on divine prerogatives. This would also explain why bringing back the dead almost always seems to go wrong somehow. Unlike God, human beings are limited, fallible creatures, and when they try and take on functions that are reserved for God they tend to screw things up pretty badly.
But while the idea that one shouldn’t try to “play God” sounds good in theory, it is not at all clear what practical application the principle has. After all, we do all sorts of things to save or prolong people’s lives without thinking that in so doing we are “playing God.” If a person flat lines at a hospital, medical personnel will typically do everything in their power to bring the person back, and they will only stop if 1) they think any further action would be futile, or 2) the person has specifically asked not to be brought back. At no point would they fail to take some action that could have brought the person back on the grounds that this would be “playing God.” If we don’t consider some of these actions “bringing people back from the dead,” it is only because we don’t believe that brining people back from the dead is possible, at least through natural means.
Nor does it seem that even fantastic methods of bringing a person back (e.g. time travel, or prayer) would involve “playing God”, so long as the methods used didn’t involve witchcraft, or other similarly occult practices, and one needn’t invoke any notion of playing God to see why bringing back the dead using such methods would be wrong. So it’s not clear that talk of “playing God” actually adds all that much to the analysis.