Acts 18:6

6 The Jews did not agree with Paul and they insulted him. So he shook the dirt off his clothes at them. He said to them, ‘If God punishes you, then you have caused it to happen. It will not be because of me. Now I will go to the Gentiles and I will teach them God's message.’

18:6Paul was showing the people that they had done a bad thing. They deserved punishment.