Is it possible that some of people that were considered in the Bible to have demons really just had a mental illness that Jesus cured? Like in Mark 5:1 where He casts out Legion, He makes it very clear it was demons but is it possible that the people back then just thought anyone who acted weird was possessed? I mean with all the things we know now, Bi-polar disorder, autism, Split-personality, Schizophrenia etc. Couldn't it be possible most people took these for demonic possessions? And that brings up the question of whether someone with a mental illness is held accountable for their sins and actions.