Judgement is not forbidden, but there is a proper way to do it. There are certain judgments that a Christian should make about things they see in life. For example, I have to judge whether a certain movie or TV program is to be deemed as acceptable in my home.
Consider these passages that tell us about judging what we are being taught:
1 John 4:1
4 Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world.
People also have to be told the truth about their sins. Recognition of our sins and repentance is what saves us:
Acts 2
36 “Therefore let all Israel be assured of this: God has made this Jesus, whom you crucified, both Lord and Messiah.”
37 When the people heard this, they were cut to the heart and said to Peter and the other apostles, “Brothers, what shall we do?”
38 Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit. 39 The promise is for you and your children and for all who are far off—for all whom the Lord our God will call.”
Look at these verses:
6 If any of you has a dispute with another, do you dare to take it before the ungodly for judgment instead of before the Lord’s people? 2 Or do you not know that the Lord’s people will judge the world? And if you are to judge the world, are you not competent to judge trivial cases? 3 Do you not know that we will judge angels? How much more the things of this life! 4 Therefore, if you have disputes about such matters, do you ask for a ruling from those whose way of life is scorned in the church? 5 I say this to shame you. Is it possible that there is nobody among you wise enough to judge a dispute between believers? 6 But instead, one brother takes another to court—and this in front of unbelievers!
7 The very fact that you have lawsuits among you means you have been completely defeated already. Why not rather be wronged? Why not rather be cheated? 8 Instead, you yourselves cheat and do wrong, and you do this to your brothers and sisters. 9 Or do you not know that wrongdoers will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral nor idolaters nor adulterers nor men who have sex with men[a] 10 nor thieves nor the greedy nor drunkards nor slanderers nor swindlers will inherit the kingdom of God. 11 And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God.
Here is something else that the church does not do for the most part:
Luke 18
15 “If your brother or sister[b] sins,go and point out their fault, just between the two of you. If they listen to you, you have won them over. 16 But if they will not listen, take one or two others along, so that ‘every matter may be established by the testimony of two or three witnesses.’ 17 If they still refuse to listen, tell it to the church; and if they refuse to listen even to the church, treat them as you would a pagan or a tax collector.
18 “Truly I tell you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.
19 “Again, truly I tell you that if two of you on earth agree about anything they ask for, it will be done for them by my Father in heaven. 20 For where two or three gather in my name, there am I with them.”
It seems that pagans are always telling us not to judge based on one fragment of Scripture.
We are instructed to judge other Christians and how to do so.
We are given courts as an instrument of common grace so that all may receive judgment.