Jesus is our example. A big part of his ministry was in casting out demons. When the presence of the Lord is manifesting strongly enough, the demons in people start to stir up. Demons often have better knowledge and theology than those who are listening to the message, as we see from this passgae.
In Jesus’ meetings, the demon was booted out, but the man remained. I have been in a few meetings where the man is booted out with his demons still in him. We need to learn from Jesus.