Absolutely agree. When I was teaching I would have regular debates with a Sociology prof and her liberal ideas. It was pretty easy to get her boxed into a corner from which she had no option but to admit she was wrong. Whenever she found herself with no escape, her response was always the same: "Well, that may be, but I don't believe it!" whereupon she would stomp out of my office. Perhaps my laughing as she left didn't help...
The other method to box them (and make them mad)
is to ask them on what authority do they base their sense of right and wrong.
IF they understand the concept, they eventually have to admit that their sense of right and wrong is nothing more than an opinion and no “better” than anyone else’s.
My favorite response in forums where liberals frequent,
when they tell me I “have no right to apply my sense of right and wrong on others” -
“so you’re saying it’s wrong for me to do that?”