This parable forced the Pharisees to answer a simple question. Can anyone drive out demons without first controlling Satan's powers and opposing him (see Isaiah 49:24–26; 53:12)?
ties up the strong man: This points to how Jesus defeated Satan. He overcame him in the wilderness temptation (Matthew 4:1–11), continued to overcome him throughout his ministry (see Luke 10:17–20), and won the final victory at the cross (see Colossians 2:14–15).