What Does the Bible Say About Judging Others?

MARK THEM AND AVOID THEM--"Now I beseech you, brethren, mark them which cause divisions and offenses contrary to the doctrine which ye have learned; and avoid them." (Romans 16:17)

SEPARATE YOURSELF FROM THEM--"Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you," (2 Corinthians 6:17)

REBUKE THEM--"...rebuke them sharply, that they may be sound in the faith;" (Titus 1:13)

REJECT THEM--"A man that is an heretic after the first and second admonition reject;" (Titus 3:10)

WITHDRAW FROM THEM--"...we command you, brethren, in the name of our Lord Jesus Christ, that ye withdraw yourselves from every brother that walketh disorderly, and not after the tradition which he received of us." (2 Thessalonians 3:6)

TRY THEM--"Beloved, believe not every spirit, but try the spirits wheth I beseech you, brethren, mark them which cause divisions and offenses contrary to the doctrine which ye have learned; and avoid them." (Romans 16:17)

REPROVE THEM--"And have no fellowship with the unfruitful works of darkness, but rather reprove them." (Ephesians 5:11)

TURN AWAY FROM THEM--"Having a form of godliness, but denying the power thereof: from such turn away." (2 Timothy 3:5)

HAVE NO COMPANY WITH THEM--"And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed." (2 Thessalonians 3:14)

RECEIVE THEM NOT--"If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed: For he that biddeth him God speed is partaker of his evil deeds." (2 John 1:10-11) *

Discernment

“Criticism for its own sake, or out of a bitter spirit, or criticism which is borne out of hypocrisy is plainly wrong, and is not motivated by the Holy Spirit. But there is another vital side to criticism” which -- “The word "criticism" comes from the Greek word "krino" meaning to judge. One of the gifts of the Spirit is "discernment of spirits" (1 Cor.12:10). The Greek word translated here as "discernment" is "diakrisis", which comes from two Greek words: dia (through or between) and krino (to judge). In other words, the Holy Spirit gifts people so that they can make a judgment between two things as to which is right and which is wrong. The specific gift of "discernment of spirits" involves being supernaturally able to distinguish between a person who is serving the cause of evil spirits and one who is serving the cause of God.

Judgments

We should make judgments which are based on the yardstick of righteousness as revealed in his Word, which look beyond mere appearance, and which are also made with the right spirit in heart. When Jesus said "Judge not, that you be not judged" (Matt.7:1), He immediately shows what kind of judgment he is speaking of there. He obviously cannot mean that we must never make any kind of judgment at all, otherwise we would not be able to fulfill the exhortations of the Word in numerous places, such as being told never to let anyone deceive us (please read Matt.24:4; Luke 21:8; 2 Thess.2:3; Eph.5:6; Colossians 2:8). If only God can judge, as you say, then how will we be able to fulfill the Apostle John's command: "Beloved, do not believe every spirit, but test the spirits, whether they are of God; because many false prophets have gone out into the world" (1 John 4:1)? Far from being wrong, judgment is actually a vital part of the Christian armory. Christ has put pastors and teachers into the church precisely to make judgments which will prevent people from being "tossed to and fro and carried about with every wind of doctrine, by the trickery of men, in the cunning craftiness of deceitful plotting" (Eph.4:14). The judgment which the Lord Jesus forbids in Matt.7:1 (as the context very plainly shows) refers to a person who makes a judgment about another person when he himself is a practitioner of the very thing which he is judging in the other! That is hypocritical judgment, which is forbidden by Christ. But the kind of judgment which builds up God's people by advising them of danger and outright falsehood is an absolute necessity.

Alan Morrison. Is It Right For Christians To Judge?  http://www.inplainsite.org/html/judge_not.html#BibleSays