"Then what advantage has the Jew? Or what is the value of circumcision? Much in every way. To begin with, the Jews were entrusted with the oracles of God. What if some were unfaithful? Does their faithlessness nullify the faithfulness of God? By no means! Let God be true though every one were a liar, as it is written,
'That you may be justified in your words,
and prevail when you are judged.'
But if our unrighteousness serves to show the righteousness of God, what shall we say? That God is unrighteous to inflict wrath on us? (I speak in a human way.) By no means! For then how could God judge the world? But if through my lie God's truth abounds to his glory, why am I still being condemned as a sinner? And why not do evil that good may come?—as some people slanderously charge us with saying. Their condemnation is just."
After having just read that Jewish ethnicity and circumcision are not means of justification, the Jewish reader may have asked himself, “Then what’s the point of being a Jew and getting circumcised?” Paul writes that Jewish pride is still important because it was through the Jewish people that God had chosen to write His laws and reveal His Word.
But many of the Jewish people were unfaithful to God, choosing to break their covenant with Him. In case the reader jumped to conclusions regarding God’s faithfulness to His people, Paul cites Psalm 51, written after David’s sin with Bathsheba, as proof that God is true to His people when they repent of their sin.
But why would I want to worship a God who punishes unrighteousness just to prove His own righteousness? This was the rhetorical question Paul asks in verse 5 in probable anticipation of argument. Paul writes that this logic only proves the unregenerate state of the minds of man. If God, being righteous, condoned sin, then He would not be a just judge. Even the most corrupt human judge would agree that there must be a punishment for crime and that that punishment must fit the crime. Sin is so opposite to the very essence of the attributes of God that it must be dealt with by a punishment fitting the crime: death.
False teachers had been perverting the gospel, accusing Paul of preaching a doctrine that encouraged its people to sin. But nothing could be further from the truth. The gospel reveals a true knowledge and understanding of one’s sinful condition. Such attributes as grace, justice, and mercy cannot be truly understood apart from the lens of the gospel.