There would need to be reliable witnesses too. I have little doubt that somebody on the Internet will claim that such things occur regularly.
Does anyone have even a halfway credible claim? Somebody besides "harrypotteristhedevil.com"?
Glad you asked. Here's the true story about a boy who played with a ouija board.
Is it that you don't believe demonic powers exist/are real, or that you don't believe that Harry Potter books would lead someone towards witchcraft.