Judging others is a serious sin, yet most people like to think they do not judge others. They may criticize, accuse, complain about, or disagree with someone, but somehow those things do not seem as serious as judging someone.
Good judgment
There are two important issues we need to distinguish here. Sometimes someone genuinely sins against us or does something clearly wrong—for example, stealing from us, damaging or destroying something that belongs to us, physically hurting us, or committing another obvious wrongdoing. In such cases, we may seek justice by going to the police or through the courts (although, as the Bible teaches, Christians are encouraged first to address such matters with fellow believers or the church leadership), so that the situation can be judged fairly and lead to reconciliation and, where necessary, restitution.
Sinful judgment
The kind of judgment Jesus refers to in Matthew 7:1 and Luke 6:37 is different. It means making a negative judgment about someone when we have no right to do so. Jesus encountered this kind of attitude on several occasions. Many religious leaders judged Him—for example, in Luke 6:7–8 and Luke 7:36–49. They judged what Jesus said, what He did, and even the way He lived. Their judgments were not always expressed openly, but Jesus always knew what was in their hearts.
Jesus warns us seriously against making such judgments about others. We have no right to condemn someone when we do not know the full situation or have not been given the authority to make that judgment.
God alone has the right to judge
We need to understand that God is worthy of all honor and worship. He alone has the right to control or make the rules by which we should live, and He alone has the right to judge.
When we accuse others, become angry with them, or are unhappy because they do not do what we told them to do, we are acting as though we were God. We are trying to control them and judging them because they have not acted as we wanted or lived up to our expectations. This attitude needs to change. Instead of judging and condemning others, we should forgive them and even ask God to bless them.
Reconsider your attitude
The quote in the question is from Luke 6:37. The full passage reads: “Judge not, and you will not be judged; condemn not, and you will not be condemned; forgive, and you will be forgiven; give, and it will be given to you. Good measure, pressed down, shaken together, running over, will be put into your lap. For with the measure you use it will be measured back to you” (Luke 6:37-38).
When we judge others, that same measure will be used toward us. We often think this passage is mainly about generosity and receiving God’s abundant blessing in return. But in the context of these verses, we should also recognize that when we give out judgment, criticism and accusations, we may find that they come back to us in abundance. That is a sobering thought. It should lead us to reconsider our attitude toward others, especially toward those we dislike or disapprove of.