Dr. J.P. Moreland:
We need to distinguish two senses of judging: condemning and evaluating. The former is wrong and is in view in Matthew 7. When Jesus says not to judge, he means it in the sense that the Pharisees judged others: their purpose was to condemn the person judged and to elevate themselves above that person. Now this is a form of self-righteous blindness that vv. 2-4 explicitly forbid. Such judgment is an expression of a habitual approach to life of avoiding self-examination and repentance and, instead, propping oneself up by putting others down.
But there is another sense of judging that is central both to moral purity/holiness and to showing tough love to another: evaluating another’s behavior as wrong, pointing that out to the person with a view to their repentance, restoration and flourishing. This form of judging another may bring short-term pain in the form of guilt, embarrassment and a experience of the need to change, but its long-term effect is (or is supposed to be) the flourishing and uplifting of the other.
Sometimes the most loving thing you can do for another is to tell him or her something hard to hear. This form of judgment is absolutely biblical. In fact, in Matthew 7:5, Jesus basically says that after one has appropriately engaged in self-examination and personal repentance, he/she is now in a position accurately and helpfully to evaluate another. This very same form of judgment is commanded in Galatians 6:1-2. It is moral confusion and cowardice to eschew evaluating other’s behavior. It is moral clarity and courage not to condemn others.
Today it is more important than ever for the church to recover and proclaim judgment as evaluation gently yet firmly. 1
Source: 1.Moreland, J. P. “Search On Judging Others: Is There a Right Way?” JPMoreland.com. J.P. Moreland, 19 Dec. 2012. Web. 1 Oct. 2015., qtd at http://apologetics-notes.comereason.org/2015/10/what-thou-shalt-not-judge-really-means.html