Not familiar with all the various sects, but traditional LaVey/Church of Satan-types are predominantly atheists, who view the devil only as a metaphor representing man's self-determinism, etc. A rejection of traditional Judeo-Christian ideology/values, and all things supernatural, in essence.
Local station interviewed a "Church" spokesman not too long ago and even the host (a zero BS, wildly judgy loudmouth) remarked how normal and down-to-earth the guy seemed: "So you're really just atheists, then, no goat sacrifices and whatnot?"
"No, none of that. That's Hollywood," dude said. "We just don't let that book tell us how we should live."