I do not believe in the supernatural, magic, ghosts or anything like that. However, I can be very superstitious about tempting fate and won’t make jokes or flippant remarks that could be interpretted as such.
For example, my partner made a dark joke about how she’d rather have cancer than such and such. I begged her not to say such things, not because the thought of her having cancer upset me (although it did), but because it feels as if saying stuff like that could make it happen.
I know of one magic spell that really works. It’s a curse:
“Nothing can possibly go wrong.”
That’s the origin of theatre people saying, “Break a leg!” The idea that it works both ways, so wishing for disaster makes things likely to go well.