You people who keep using this quote mangle the meaning by taking it out of context. Here is the whole quote:
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Romans 2:
Therefore thou art inexcusable, O man, whosoever thou art that judgest: for wherein thou judgest another, thou condemnest thyself; for thou that judgest doest the same things.
2 But we are sure that the judgment of God is according to t***h against them which commit such things.
3 And thinkest thou this, O man, that judgest them which do such things, and doest the same, that thou shalt escape the judgment of God?
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Matthew 7:
Judge not, that ye be not judged.
2 For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again.
3 And why beholdest thou the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye?
4 Or how wilt thou say to thy brother, Let me pull out the mote out of thine eye; and, behold, a beam is in thine own eye?
5 Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye.
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The context of the quote is that the person judging is a hypocrite who is committing the same sin as is the person he is judging. The command to "judge not" is not given to anyone and everyone who judges. It is only given to hypocrites who are committing the same sin that they are judging someone else for.
Consider this search of the New Testament on the word "Judge"
http://www.biblegateway.com/keyword/?version=KJV&search=judge&searchtype=all&language1=en&spanbegin=47&spanend=73&startnumber=1and see all the contexts of Judge that the Bible talks about. There are many passages that teach when we should judge and when we should not. Many say that we should not judge others, but there are passages that command us to judge others under certain circumstances.
Such as: I Corinthians 5:3-13, and I Corinthians 6, 1 Corinthians 11:30-33,
2 Thessalonians 3:
6 Now 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.
10 For even when we were with you, this we commanded you, that if any would not work, neither should he eat.
11 For we hear that there are some which walk among you disorderly, working not at all, but are busybodies.
14 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.
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2 John 1
5 And now I beseech thee, lady, not as though I wrote a new commandment unto thee, but that which we had from the beginning, that we love one another.
6 And this is love, that we walk after his commandments. This is the commandment, That, as ye have heard from the beginning, ye should walk in it.
7 For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist.
8 Look to yourselves, that we lose not those things which we have wrought, but that we receive a full reward.
9 Whosoever t***sgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
10 If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed:
11 For he that biddeth him God speed is partaker of his evil deeds.
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You people who throw that quote around "Judge not, that ye be not judged," need to inform yourselves of what it really means, and make a valid argument to support your position on wh**ever the subject is, not just use that quote to shut up someone you disagree with.