The LDS church has a weird habit of baptizing dead people into their faith — and now you can get even. Atheize anyone!
It works, too! I atheized Brigham Young, and next thing I knew, his ghost was hanging about whining about how I'd gotten him kicked out of Mormon heaven and how all his celestial wives had laughed as they tossed his newly godless patriarchal butt off out of their palace. That may sound like a bit of an annoyance, getting haunted out of the deal, but really, it's no problem — just remind them that they don't believe in the supernatural, and you might get a brief look of quizzical startlement before they vanish in a puff of ectoplasm. Easy.