Most non-Christians are very quick to claim that Christians are not supposed to judge. They say it with a sense of arrogance, as both a reminder and a reprimand. One of the key verses used to promote this false teaching is found in Matthew:

Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye?
— Matthew 7:3

The wrong interpretation of this text is that Christians are not allowed to judge. The correct understanding of this passage is that believers are not supposed to give instructions to someone if they are also struggling with that same sin.

For example, I am not going to take money advice from a poor person. I’m not going to take weight loss tips from an overweight person. And, I’m certainly not taking safety tips from a shop teacher missing a finger. It’s just not going to happen. These people have no authority to give a lecture on those subject matters.

This passage teaches that before you can instruct your brother, make sure you know what you are talking about so that you can give sound advice. I think this is what David meant in Psalm 51:4 when he refers to God as justified when He judges:

Against you, you only have I sinned and done what is evil in your sight, so you are right in your verdict and justified when you judge.
— Psalm 51:4

The beauty of God’s judgment is that God is a righteous judge who is without sin. God speaks with authority with no sin and no mistakes. God is the ultimate judge!

Have you ever worked with someone who makes mistakes? Maybe they forget little details here and there; perhaps they misplace items. The truth is, after a while, it becomes hard to trust them. In some ways, they have lost your trust. You want to believe them, but you have your doubts.

Then, there are those people who never seem to forget anything; they never make mistakes. If they told you your birthday was on the wrong date, you might believe it because they are never wrong. David reminds us that God is justified when he judges because he is never wrong. You can rest easy trusting the wisdom that God gives us.