We all know that those who do things that are against the will of God will become evil and are not allowed to enter the kingdom of God. They will be punished in one way or the other.
Evil is those who do not respond to the right path and move to the ways that the evil prepares for them. Evil is the Demons called Satans, where Hell is their home, the home of fire and death.
As per the bible, demons are the Angels that are fallen completely away from God, going against the will and wish of God. They are completely out of hope from God and pushed down to hell from Heaven above.
Demons are those evil spirits, that lead people to a world that is against God and make your mind full of evil thoughts and only sins.
Demons only want people to get punished and push you to dangers and watch you die and suffer.
Demons are the ones that give you fake promises and expectations and will make you go mad, where when you end up in danger, they will run away from you and never think of saving you from any danger that is being created by them.
When we humans decide to continue with a mind that is evil and that is against the will of God, he or she will be out of the hands of God and will be made to live in hell with the demons.
In a nutshell, Demons are the spirits that are terminated to work under God. They are the ones who do things that are against the will of God.