Well, many of his stories have some Sci-Fi feel, as he tends to try to have some explanation behind most things, even if it's not revealed in the specific story. Similarly, religion is part of most communities, so it tends to crop up as well. But in general, he tries to have character driven stories much of the time, so it's possible to find some that are less religious based.
A few I've read that seem to fit your criteria:
- Firestarter (Psychic based powers)
- The Dead Zone (Again, Psychic powers)
- The Running Man (which inspired the movie of the same name)
- Cell (from what I understand; I've never read it, but it's a technological apocalypse.)
- Under the Dome (A reworking of Lord of the Flies, basically)
- Possibly Carrie, as, like Firestarter and Dead Zone, it's more related to Pyschic powers. Religion is a major component of it, but not as any of the explanation, but more as a driving force behind character actions, like many of his stories.