We must judge others by God's standards of fairness. It's in the Bible, Isaiah 11:3-5, TLB. "His delight will be obedience to the Lord. He will not judge by appearance, false evidence, or hearsay, but will defend the poor and the exploited. He will rule against the wicked who oppress them. For He will be clothed with fairness and with truth."
Your judgments of others come back to judge you. It's in the Bible, Matthew 7:1-2, NIV. "Do not judge, or you too will be judged. For in the same way you judge others, you will be judged, and with the measure you use, it will be measured to you."
Judgment is appropriate when confronting sin. It's in the Bible, I Corinthians 5:12, TLB. "It isn't our job to judge outsiders. But it certainly is our job to judge and deal strongly with those who are members of the church, and who are sinning in these ways."