The story is in Luke 11:12-26 but can also be found in Matthew 12. Jesus stopped and cast out a devil from a man who was mute (could not speak). After that the man could speak and the audience wondered. Why wonder? Why not marvel?
This was another opportunity for the religious leaders to jump Jesus and make accusations. “He casteth out devils through Beelzebub the chief of the devils.” Then they get a little ugly and say something about showing them a sign from heaven. Jesus answers and says that a house divided against itself cannot stand. He goes one step further and says that if he casts out devils by the devil, then who are their sons casting them out by?
In verse 21 Jesus is pointing out that a strong man who is armed (the devil) is at peace in his palace (the man who is possessed). But when one who is stronger (Jesus) comes along and takes all that he has (the man is no longer possessed) the devil is evicted from his spoils (verse 21,22).
Then Jesus speaks to the observers, the audience. Remember it said ‘wondered’ in verse 14? Jesus says that they are either for him or against him. No fence sitting allowed. Then Jesus addresses the man. He warns him that he is a vacuum right now and must fill it with something or else, the devil will return and bring more spirits with him.