Yeah, it's that moment when you know that there's no response you can think of that isn't either something you know isn't true, or something that directly undermines the validity of your ideology.

So you say nothing, and silently acquiesce.

Maybe you go home and and you search for answers. Maybe you ignore it for months. But enough interactions like that and the only kind of person who sticks with their former beliefs is either some kind of psycho, or some kind of retard.