I agreed with this at first, but actually, no. Belief in the supernatural doesn't require belief in gods, spirits or any non-human agents. You could just believe that humans have some supernatural abilities like reading each other's minds. When trying to explain these abilties, only reductionists will conclude that there's some third party agent like a simulator setting things up. Non-reductionists will just accept that being able to read minds is part of how this ontologically fundamental mind stuff works.