A linguist I read quite a while ago made a suggestion to grammarians. He suggested that they get a needlepoint image of the word "ain't" and frame it and hang it on their wall. The reason he suggested that they do this is because the battle against ain't is probably the only battle linguists have ever won. Reminding themselves of this would be an appropriate lesson in humility.
For similar reasons, I think that American liberals would do well to frame a needlepoint of the figure "20%" on their walls. Why? Because that is the proportion of the population that reliably self identifies as liberal. That's it. Four out of five Americans disagree with liberalism some or all the time.
In that regard (and I'm thinking of things like this), could I humbly suggest that liberals are ill-advised to be insulting the people who disagree with them? As a controversial Catholic saint once said, you can catch more flies with honey than vinegar.