Paul gets back to the subject of following rules in this chapter. Any time people use some sort of rule to judge others, they are acknowledging God’s right to judge them. The church in Rome was made up of Jews and Gentiles (non-Jews) just like the Galatian Church. Although the Jews had many more rules than the Gentiles, and those rules had been handed down by God, the Gentiles had rules too. Even if people are unaware of God’s rules, they know there need to be rules and that people who break those rules should suffer a consequence.
Paul sees that people want God to be forgiving toward them, but judge those they don’t like harshly. The danger of us looking down on someone else for their sin is that we condemn ourselves for our own sin. We would do well to view our own sin and the sins of others as serious rebellion against God that has already been forgiven.