“Judge not, lest you be judged”- Matt 7:1-2
This verse is the favorite Bible verse of non-Christians, to fend of criticism for violating Christian standards of conduct.
When we talk about judging, we are talking about the claim that a person deserve something bad for doing something bad. Unless we are charged with the job of assigning criminal punishment, then we have to recognize that we lack knowledge of people's circumstances to know what someone deserves. On the other hand, I don't think that anti-judging mandate makes it impossible for us to say that certain types of actions are morally wrong. We could use the same reasoning for theft, or murder, or adultery, for example, and argue that we can't judge people who do those things.