And they went into Capernaum, and immediately on the Sabbath he entered the synagogue and was teaching. And they were astonished at his teaching, for he taught them as one who had authority, and not as the scribes. And immediately there was in their synagogue a man with an unclean spirit. And he cried out, "What have you to do with us, Jesus of Nazareth? Have you come to destroy us? I know who you are--the Holy One of God." But Jesus rebuked him, saying, "Be silent, and come out of him!" And the unclean spirit, convulsing him and crying out with a loud voice, came out of him. And they were all amazed, so that they questioned among themselves, saying, "What is this? A new teaching with authority! He commands even the unclean spirits, and they obey him."
Don't you simply love the response of the crowd as they connect Christ's teaching to the demonic exorcism. I wonder what he was teaching that day that so agitated the demon? Perhaps the new teaching was about how the kingdom of God is not about following the law but about loving God and your neighbor? Demons don't mind a bit of legalism and rules - they love to see Christians get focused on themselves and ignore outsiders.
The whole topic of demons is a pretty dicey one to talk about. Some believe that demons do not exist and never have. Some see a demon under every rock. I think that the balance is somewhere in between and spiritual discernment is required to know when demons are influencing a person and how the demon is to be rebuked. In such times it is wise to respond in a simple and direct manner as Jesus did by speaking a word of rebuke.
Teach me Lord. Help me to trust the discernment you have deposited in my life.