i once had dinner with a guy that said he was lucifer inhabiting a human body. it's a long story but he gave me reason to believe him, including being able to read my thoughts, know my past (i only met him that night) and manifest things on the spot. He was very very wise and we talked a long while. His answer to that question was that Satan was not an entity (conscious being) but an idea. He described it as a direction away from all that is right and true. He argued that there are a great many spirits that want you to think they are "satan" because they know it'll garner respect.