That verse works about as well as this one does...
...judge not...
You FOOLISH Galatians! Who has bewitched you?
Galatians 3:1
Proverbs 18:2
A fool has no delight in understanding, but that his heart may discover itself.
When you specifically call a person a fool, you are in violation of Jesus’ specific command. Calling someone’s actions foolish, however, is quite different. Take note of what Job said to his wife, when she counseled him to ‘curse God and die.’ He said, [quoting from memory, so a word or two may be slightly off] ‘You speak as the foolish women speak.’
In that statement Job did not sin. He did not call his wife a fool. Rather, he pointed out that in one specific statement she spoke as a foolish woman would speak. There is a big difference between labeling a person a fool—thus violating a direct command of Christ—and pointing out that a specific action or expression is foolish.
It isn’t possible—or at least it is highly, highly unadvisable—for Christians to set aside the direct, specific commands of Jesus. It is very dangerous to even contemplate doing so. I hope no one on this thread considers doing so. It’s just a very, very bad idea.