The devil has found fertile ground in mankind because of the frailties of human nature. And with man’s help he has developed powerful tools of manipulation in his pursuit of destroying us. Let’s face it, he’s had plenty of time to figure us out. How does he go about this business of enslaving people? Well, just as God mainly works through people in all He does on this earth, Satan and his demons work through people in wreaking their havoc.
Further, it goes without saying that demons, being spiritual creatures, have direct access to man’s immaterial nature. They have no trouble taking advantage of a person’s dead spirit, since people naturally lay themselves open to attack when devoid of the life of God within.
Jesus talked about a man who got rid of an evil spirit only to have it, along with seven others, enter once again when it returned to find its house “unoccupied, swept, and put in order.”(Matthew 12:44) Many other passages in Scripture make it clear that demons are able to exert powerful influence over the heart, oppressing and sometimes even possessing people.