Satan is a construct of an unbalanced belief system. He was invented so that people didn't have to take responsibility for their own negative actions. If more people focused on the light and the good, we would not have the evil that is done in this world. It is those who focus on the dark that bring bad things forth.
Every one of us has a dark side as well as a light side. To give the dark side a proper name and to single it out means you are focusing on it and placing importance on it. Don't do this. What you focus on expands and becomes a much bigger part of your life and a part of this world. When you don't focus on it, it shrinks into the background and becomes insignificant.