If there is a member of your community that you know is acting against God, you should confront him.
Paul says to take it to the public, embarrass and humiliate him. I disagree with Paul here, but maybe because I hate being embarrassed. Maybe the threat of embarrassment is needed to keep people from doing harm to themselves? I’m not sure, I just think there is a way to confront people without making them feel like lesser humans.
But Paul says that we need to keep our community in check. He recognizes that outsiders may go against God, but we need to always seek integrity and holiness if we claim those things.