We are here in a fallen world to know good and evil.
Moses 4:28 And I, the Lord God, said unto mine Only Begotten: Behold, the man is become as one of us to know good and evil;
Put differently, we are here to learn to correctly judge between good and evil. This is one of the main purposes of mortality, as stated from the very beginning of the world. Insofar as we learn to do that correctly, we will be able to make choices that will lead us to eternal life. Insofar as we do not, we will make choices that lead us to destruction. This was summed up by Christ in the phrase "Judge not lest ye be judged."
It may be surprising to learn that what Christ means by the phrase "Judge not lest ye be judged" is that we must learn to correctly judge good from evil or we will not gain eternal life. Where greater clarification is added by the JST the meaning becomes much clearer.
JST Matt 7:1 Now these are the words which Jesus taught his disciples that they should say unto the people.
2 Judge not unrighteously, that ye be not judged; but judge righteous judgment.
Thanks to the JST, the meaning of Christ's phrase here becomes much clearer. Christ's commandment here is an imperative to judge righteous judgement, and a command to abstain from judging unrighteous judgment. I repeat that judging righteous judgment is given as a commandment by Christ.
Note that judging righteous judgement is not only given as a commandment, it is given as a commandment by Christ personally, and his disciples are to teach the people to judge righteous judgement. Put differently, the people must be taught to call good good and call evil evil. They are to correctly judge right from wrong. They are to judge by the light of Christ to know good from evil as they know light from day. That is because knowing good and evil is one of the most fundamental things we have to accomplish in mortality. We are here to be as Gods, knowing good and evil. It is a critical part of the whole test of mortality. We only pass this test as we surrender our own notions of good and evil in favor of Christ's.
Judging righteously is using God's judgement to determine what is right and what is wrong. It can be accomplished by searching diligently in the light of Christ.
The Lord says "judgement is mine". He knows right and wrong perfectly. Righteous judgement is to judge as the Lord judges, by searching in the scriptures and the light of Christ for his inspiration. When we judge by revelation, we always judge righteous judgement.
We are not taking judgement away from God if we judge a matter by his word or by the light of Christ. We are doing the opposite, we are leaving judgement in his hand, seeking his judgement of the matter and accepting that rather than judging by our own wisdom, or even worse, by worldy philosophies and ideas.
The person who refuses to acknowledge good as good, or to acknowledge evil as evil is breaking Christ's commandments on judging. They are not judging righteous judgement. They are not calling good good, or calling evil evil.
More commonly, the commandment to "not judge" is tacitly taken to mean that saying anything is wrong is evil. That is actually judging unrighteous judgement, and violates Christ's commandments on judging. That is because it universally misjudges everything evil. Calling evil good, or even refusing to call it evil, is not righteous judgement. It is taking judgement away from Christ, and using a worldly idea to judge in his place.
We must turn to him for our judgement of good and evil, surrendering our worldly notions or right and wrong completely to his inspiration and scripture. Then we can judge righteous judgement, as he commanded. Then we can avoid being judged, because we will know good and evil and know how to choose the good.