I've only seen a "demon" once a couple of years ago it was just hanging out in the corner of my bedroom glaring at me. I figured it wasn't real so i just watched it until my mind got distracted and it went away. I have a lot of dreams about demons though and a lot of sleep paralysis involving demons coming after me and or squashing me.

I just try to remember that logically demons don't exist. They're just a product of your mind making stuff up. I don't know why our minds have to make up such scary things sometimes but if you're able to keep perspective and understand them as just a product of your mind they lose a lot of their power over you and your thinking.