 You approach them privately first, and if that doesn't work, obviously then you recruit another witness, not to gang up against your fellow believer in Christ, but to plead with him or her, listen, it seems to me like you're engaged in a pattern of unrepentant sin. We love you. We want you to be out of that. Our enemy is fierce, but we also must acknowledge, still from verse 8, that Satan is also furious.