“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. We know that the judgment of God rightly falls on those who practice such things.” -Romans 2:1–2
In order to demonstrate, in fact, that none are righteous before God, in chapter two, Paul turns his attention to the hypocrites and the religious (sanctulos) in general, and his own people, the Jews, in particular (vs. 17).
Calvin describes this group of people as they “who dazzle the eyes of men by displays of outward sanctity, and even think themselves to be accepted before God, as though they had given him full satisfaction. In other words, Paul is speaking now to those who put on airs of righteousness outwardly, but in the privacy of their homes or the privacy of their minds (for that’s where sin takes place Cf Matthew 5:19-22) do the very same thing. Therefore, they too are ἀναπολόγητος (without excuse).
In verse two, Paul reminds them that God’s judgment rightly falls on those who practice such things. By rightly, he means according to the righteous character of God and the truth of things regardless of who commits it. There is no class of people who receive special privilege, there is no potential for God to make an error in judgment, and there is not way the judge of all the earth not do justly and overlook even the smallest sin. All sin will be judged.