What Is A Demon
Definition from the dictionary:
an evil spirit or devil, especially one thought to possess a person or act as a tormentor in hell.So we're talking about an evil spiritual being. Now I don't know if you've met one of these most likely you did not. There is a reason science doesn't believe in spirits, ghosts or demons. For a long time, scientists tried to debunk all these occurrences for normal natural phenomena, like the heat exchange and the change of the size of materials resulting in certain sounds or for the brain playing trickery due to missing sleep or maybe even electromagnetic waves resulting in something. So technically demons don't exist.
If the Believe Counts
However if the approach this topic with the mindset I've established myself and encourage others to give a benefit of a doubt we can assume demons exist just because there are people out there who believe in them. Any movie, film, imagery or other media that presents the author's opinion or thought of what could be would be enough to increase the chance of one to actually exist. So let's assume they do exist for the sake of this post.
The Encounter
The encountering may be any at hand. You could meet one during your spiritual journey, find it at some forgotten long uninhabited home or workplace or even at an old spiritual place. So exploring places humans don't belong may or may not result in this. However, chances are extremely slim you'll pick one up even if it's shown like that in movies. Movies may or may not depend on real happenings but I'd assume at least 70% of them are made up. Another way to encounter a demon is by summoning. This can be through evocation (manifesting outside) or invocation (manifesting inside or from the inside). Luckily there's nothing to worry about evocation or invocation of a malicious spirit. You can't summon something stronger than you if you do not use tools or aids. So if you think your rituals through there's nothing to worry about.
How Spiritual Power of a Demon Supposedly Works
I already mentioned this in the Goosebumps post. An entity gains power the more thought and attention it is given. This will mostly count for demons too. The more attention and thought you give it the more powerful it becomes. This is not the only way demons gain power. It is commonly known that evil siphons fear so to speak. Whether it's the case due to people knowing or believing in this or if it really is doesn't matter. Fact is you should know that a demon may gain in strength if you feel fear or if you're scared.
Knowledge Is Power - The Greatest of Mankind
The saying "knowledge is power" plays a great role here. We now know that demons gain power through attention and especially through fear. This is what we can use against the demon. If we don't take the demon serious and maybe even laugh at it by heart it can easily be weakened and a weak demon can be banned.
"Laughing is the best way to ban"The problem with this? If you have your first encounters with a demon and it goes crazy all-out throwing stuff around or attacking, are you able to laugh it off in all seriousness? Can you actually stay positive enough and believe in yourself to be stronger? These questions play a huge role in something I would call "The Believe Fallacy of Magic". The power of magic is unlimited they say. You can do anything you want with this power. If you're able to.
How to actually ban the demon is another story. One I don't know as of now, but I assume it depends on the culture and what's a way that you find appropriate.