Than it isn’t an argument and you don’t have anything to lose. If someone is being preachy and are completely uninterested in your positions just let them talk. Keep asking questions and a surprising thing happens: Everyone else in the room will suddenly realize the person talking is an idiot.
You’ve got to be careful though. Some people, i.e. many creationists, will just take that as an invitation to ramble ad infinitum.
Than it isn’t an argument and you don’t have anything to lose. If someone is being preachy and are completely uninterested in your positions just let them talk. Keep asking questions and a surprising thing happens: Everyone else in the room will suddenly realize the person talking is an idiot.