Opinion on the evil

Hi!

So, I learned that demons are not evil and would not harm someone who asks them for help (pretty much just like angels or any deity, i believe).

How do you recognize an evil spirit then? If demons are not those who cause you pain, how to interpret the existence of demonic possessions and/or bad interactions?
What is an evil spirit if not a demon?
And how do you get rid of one (either an evil spirit or a demon)?

Another thing:
How would it look if at some point you decided to leave this path? Because from my experience about leaving religions nothing really happens, you just stop praying and such. But what if you stopped interacting with the demons you would possibly talk to before, and ask them for help? And what if you converted from that to let’s say Islam? Or any other religion that ‘demonizes’ them.

They might not be “evil” as much as just predators or parasites that are interested in you as food.

They make you feel like shit, is the short answer. “The proof of the pudding is in the eating.”