Paul here is talking to the Jews. They judged others who didn't have the Law, thinking that, because they had it, they were immune from God's judgment. They didn't realize that by judging others, they were only condemning themselves because, while they judged others, they did the same things. So, by judging others, they just ended up condemning themselves! They were not escaping God's judgment because God's judgment is based on truth.
Why do people judge others? It is because they are stubborn and unrepentant. And because of this, they end up showing contempt for God's kindness, forbearance, and patience with sinners. People judge others because they don't think God's judgment is reliable or quick enough. But God's judgment is postponed because he wants everyone to repent and be saved.
God's word should never be used to judge others. We should remember that we, too, are sinners and that we stand only by the kindness and patience of God. So, we should never judge others but guide them to repentance with the word of God.
Application: Father, you are full of kindness, forbearance, and patience with sinners because you want them to repent. Help us not to hold your kindness in contempt but to repent and show your patience and kindness to others.
One Word: God wants us to repent!