I am not entirely sure what most people, especially liberals, are thinking when they say that you are being judgmental. Perhaps they mean that you are looking upon another human being with disdain. Or perhaps they mean that you are calling someone’s actions morally reprehensible. That kind of a claim is often accompanied by a negative emotion aimed at the person you are condemning.
The most puzzling use of the term “judgmental” is when it is used to describe a person who is simply affirming something as true. For example, if I simply say “I think Jesus Christ is the only way to heaven” I find it mind boggling that I would be called judgmental for simply stating my position. In these cases, “judgmental” simply means, “you disagree with me, thus you are judgmental”. If that was a legitimate use of the term “judgmental” then everyone is judgmental about something as we all disagree about lots of things.