I am not an athiest but I have had things happen that I cannot explain. We lived in an apartment above another sister. At night, about 2 am, this sister would call my mom and scream at her because we were making racket up there. Of course everyone was alseep so no racket was done by us. We would also hear people walk up the stairs to our front door and we would go to answer the door to a totally empty hallway. I once saw a woman standing in the living room. Apparently an old woman had died in our apartment at one time. While at this apartment I also had furniture (my desk chair) lift into the air and go in circles. And one time I heard my sister come through the door, jump into the bottom bunk, and situate herself and go to sleep. I went to talk to her in the morning and she was not there nor was her bed rumpled. I asked her about it later and she had slept in the other bedroom.
I'm not sure how much of this was real or not. At the time I was interested in astrology and the chair and my sister thing happened during this time. Was it real? I have no idea, it could have been my imagination also because Witnesses used to sit around and talk about demons all the time. Could have come from fear and hallucinations for all I know.
Oh and just last wee......I went into the kitchen and the pantry door came open and almost hit me on the nose. I think it was the demons who through my little dog in there to go after the dogfood in there so she could scare me. I don't know. LOL