Scripture That Condemns Hypocritical Judgment
Judge not, that ye be not judged. For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again. And why beholdest thou the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye? 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? 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. (Matthew 7:1-5)
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. But we are sure that the judgment of God is according to truth against them which commit such things. 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? (Romans 2:1-3)
Examples of Scriptures That Call Us to Judge Others
Judge not according to the appearance, but judge righteous judgment. (John 7:24)
When I say unto the wicked, Thou shalt surely die; and thou givest him not warning, nor speakest to warn the wicked from his wicked way, to save his life; the same wicked man shall die in his iniquity; but his blood will I require at thine hand. Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul. (Ezekiel 3:18-19)
Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone : if he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church : but if he neglect to hear the church, let him be unto thee as a heathen man and a publican. (Matthew 18:15-17)
Sometimes, We Need to Limit Judging to Those Within
It is reported commonly that there is fornication among you, and such fornication as is not so much as named among the Gentiles, that one should have his father's wife. And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you. For I verily, as absent in body, but present in spirit, have judged already, as though I were present, concerning him that hath so done this deed, In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ, To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus. Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump? Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us: Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth. I wrote unto you in an epistle not to company with fornicators: Yet not altogether with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must ye needs go out of the world. But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat. For what have I to do to judge them also that are without? do not ye judge them that are within? But them that are without God judgeth. Therefore put away from among yourselves that wicked person. (1 Corinthians 5:1-13)
When Judging Others Is a Sin and When It Is Not
Where judging others becomes a sin is when it is hypocritical or self-exempting (Matthew 7:1-5  and Romans 2:1-3). The Scripture often calls us to judge. For example, Scripture calls us to confront sin (Ezekiel 3:18-19, Matthew 18:15-17, and 1 Corinthians 5:1-13). Also, we need to tell a person that he is lost and going to hell, even if he believes (wrongly) otherwise, assuming that this is the case. Also, see my page on salvation.
 All scripture references are from the King James Version unless otherwise noted. Please see my about page for why I chose this translation.