To know what he is you must know what he is not

Do devils or demons really exist? People who use negative realities, negative emotions, and negative evil descriptions when describing their world, they are our enemies. These are the ones who are the true creators of "devils" and "demons."
They see you and decide you don't fit, to their preferred way, or desired method of doing things. So they MAKE you bad. They say you are bad, then they do bad things to you, to try to change you, to mould you in to what you "should be." If you resist or fight back against this "moulding," this very act of resistance, on your part, is seen as an act of aggression, evidence of your evil behaviour. You have become a manifestation of the demons that they fear.
Their hate for you has determined their actions towards you. And also influences your response towards them, often being human, we hate those hating us. Spreading the disease of hatred, even further and doing the work of destroying love, even more thoroughly.
Instead if people lovingly try to "change" others, rather than use anger, fear, hate and aggression just to prove that these very emotions are wrong. If they are wrong, don't use them as tools to prove they are wrong. Let a person stick his own hand in the fire to learn of the error of burning, rather than burning him alive in an attempt to prove your point. In other words don't "fight fire with fire" unless you want to burn the whole world.