"Judge not lest you be judged..." Anyone who has been an active Christian for long has had this statement thrown at him by unbelievers and has agonized over what he is allowed to say and do. In fact it paralyzes many of the devout and hinders others by indecision.
Our troubles with judging come from two sources, the devil and our own sin nature. The devil is waging ideological warfare against the integrity of the church (II Cor.10:3-5). He tries to influence us either to cast aside justice out of love or to cast aside love out of justice (I Cor. 6:2). He is influencing us to condemn sinners outside the body and tolerate sinners inside the body (I Cor. 5:12). He is always accusing us of our sins, to render us ineffective (Prov. 28:1).
Our hearts can get us off track by attributing to the invisible God some of the characteristics of our parents. If our parents were harsh and condemning, our first impression of God and any other authority figures will be that they also are harsh and condemning. If our parents were unloving and uncaring, we may feel that we must compensate for this flaw in all authority figures including God. If we wish to become imitators of God, we must first understand what He is like.
But even then we can make Lucifer's mistake of counting equality with God a thing to be grasped. We can and should imitate God in all ways, except one -- His sovereignty. In our hungering and thirsting for righteousness it is easy to become caught up with wishing the worst for evil-doers. We must beware lest our anger entices us to condemn them (Job 36:17-18).
So what does "judging" mean?
First off, the verb "judge" cannot mean the same as "discern" or "discriminate". Jesus said, "Be ye wise as serpents..." (Matt. 10:16). Proverbs give us ways to discern evil people from good people. Jesus commended those who were discerning (Rev. 2:2). So 'judge not' doesn't mean that we are to hide our eyes from sin in our midst and think happy thoughts all day. The apostle Paul said, "Be anxious for nothing, but in everything with prayers and supplication (with thanksgiving) let your requests be made known to God; and the peace of God...will guard your hearts and minds through Christ Jesus."
Second, it cannot mean that we can never utter criticism. Jesus Himself told us to rebuke a brother who sins (Luke 17:3). Jesus was known to criticize some of his fellow Jews (Matt. 23). The apostle Paul criticized the apostle Peter (Gal. 2:11) and a magician (Acts 13:10). He told Timothy to rebuke when necessary (II Tim. 4:2).
Third, 'judge not' doesn't mean that we can never actively reject someone. Jesus rebuked a church for not doing so (Rev. 2:20). Jesus tells us to disfellowship a brother under certain circumstances (Matt. 18:17). Jesus personally ejected merchants from His Father's house (Matt. 21:12). The apostle Paul ordered a person to be driven out of the church (I Cor. 5:13).
Jesus said, "Judge not that you be not judged. For with the judgment you pronounce you will be judged,..." The apostle Paul said, "Therefore you have no excuse, O man, whoever you are, when you judge another; for in passing judgment upon him you condemn yourself, because you, the judge, are doing the very same things." (Rom. 2:1) These words are true and right. But what is the essential criterion for deciding whether we are judging or not?
I have concluded that while we can't judge, the Holy Spirit who is in us and who is God can judge righteously. Jesus said, "I can do nothing on my own authority; as I hear, I judge; and my judgment is just, because I seek not my own will but the will of Him who sent Me. (John 5:30)" The apostle Paul wrote, "The spiritual man judges all things, but is himself to be judged by no one. 'For who has known the mind of the Lord so as to instruct Him?' But we have the mind of Christ [so as to instruct us]. (I Cor. 2:15-16)"
In Matthew 7 Jesus goes on about judging, saying, "first remove the plank from your own eye and then you will see clearly to remove the speck out of your brother's eye. Only when you are confessed up and righteous before God should you even think of judging your brother. Jesus reiterated this when he told the Pharisees, "Let he who is without sin cast the first stone."
How about forgiving? Aren't we always to forgive? Jesus said that if we don't forgive people their sins against us, we can't expect God to forgive our sins. How can we do that and rebuke our brother as Jesus told us to do in Luke 17:13-14? We are not to judge but forgive; God will rebuke him, and might use us as a channel to do so if we are right before Him.
If this is true then it is very important that we learn to listen to the Holy Spirit within us. As the apostle Paul wrote, "...we have not ceased to pray for you, asking that you may be filled with the knowledge of His will in all spiritual wisdom and understanding, [in order] to lead a life worthy of the Lord,.... (Col. 1:9-10)" Later in the same letter, he wrote, "Let the word of Christ dwell in you richly, as you teach and admonish one another in all wisdom,...."