Therefore you have no excuse, O man, every one of you who judges. For in passing judgment on another you condemn yourself, because you, the judge, practice the very same things. (ESV)
There is something in us that likes to compare ourselves to others. We love it when we hear of someone who has done some grave sin and we can pat ourselves on the back and say, "I would never do that." If you were to ask the average person on the street if they think they are a good person they would probably say yes. If you ask them why they will inevitably compare themselves to others.
This insistence on righteousness based on comparing ourselves to others is not an adequate standard at all. Our standard of holiness is no where near God's standard. In this verse Paul condemns those who pass judgment on others. In so doing they condemn themselves. Those who judge are guilty of the same sins.
At first we want to disagree with Paul. We have read the list of sins he mentioned in Chapter 1. We might say, "I have never murdered anyone." But compare that with Jesus' words. In his Sermon on the Mount he talked about how telling someone you hated them was the same as murder. He also said that looking with lust at a woman was the same as adultery. God's standard is higher.
God is interested in the heart. Whether or not we have gone through with the actions we are still guilty because all of us have committed sins in our heart. One of the reasons that Jesus came was to show us that we simply cannot fulfill his perfect law of righteousness. Only Jesus could do that. His perfect life was lived for us. Only in him will we find holiness.
Do you find yourself comparing yourself to others in order to feel righteous? That kind of judging is futile. Admit your sinfulness. Rely on Christ's work on your behalf. He will give you his righteousness and you will become so much easier to live with.