Do demons inhabit the souls of men and women?
Well, no. Demons inhabit the pages of mythology, fantasy novels and some amusing TV series (I am a Whedon fan) but they are not found in the real world. We human beings sometimes try to enhance our own self-image through the myth that people are innately good (the milk of human kindness flows in our veins) and hence, a particularly horrible crime must be caused by some non-human, supernatural evil. But actually, we human beings are capable of any evil. We are born selfish and some of us grow up to be sociopaths. No demons are required.