These words from the sermon on the Mount (Matt. 7:1-5) turn out to be some of the most famous words Jesus said, but unfortunately not always for the right reasons. These words are often used as a bludgeon against those who are raising concerns about objectionable or sinful conduct. These is obviously a misuse, since some judgement is required as we go through life.
While this passage is commonly misused, it does have a true use and Jesus’ words are to be carefully considered for what they do mean, not just what they do not. The lesson here is to judge fairly, rightly, and with a generous spirit since that is how we will be judged as well. The whole teaching of Jesus on the sermon on the mount is to be generous in our giving and helping of others, and our treatment of them even if they are different from us or have done us harm.
This generosity of spirit is to extend to the way that we judge them as well. Think of how unfair it is the judge people based on standards that they do not know, or to excuse our friends and family (and especially ourselves) but to never excuse faults in others. The Pharisees were especially known for finding all faults in others but never finding faults in themselves. Or, as Jesus brings up with the log (beam) and the speck, making much of small faults in others while overlooking large faults in those that we favor.
“The commandment is leveled at rash, censorious and uncharitable judgments, and that fault-finding spirit or disposition which condemns upon surmise without examination…forgetful that we also shall stand in the judgment and shall need mercy. (McGarvey, Fourfold Gospel.”)