For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them (Rom. 2.14-15 ESV)

Most commentators (of that I know) have now recognized that Paul is not saying that unredeemed Gentiles are keeping the Law. That thought alone makes no sense when reading the text. What some want to claim is that there are “good” people among the Pagans who display moral perfections of some degree. This notion is far different to the inviolate standard biblical doctrine expressed in the next chapter of Romans: As it is written: There is no one righteous, not even one (3.10 NIV).

Paul is not describing a “common” grace if the recipients are keeping the Law. Rather, Paul speaks of special, or redemptive grace since the individuals are keeping the Law. The Mosaic Law, rightly understood, is holy, righteous, and good. These are redemptive and not common by definition. “Common grace” is a phenomenon that occurs to all people regardless of performance. It is spoken about by Jesus in Mt. 5.45b: He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous (NIV). “Common grace” being indiscriminate defines “common.”

“Common grace” is condemnatory as seen by Paul’s address to the people at Lystra: We are bringing you good news … In the past, he let all nations go their own way. Yet he has not left himself without testimony: He has shown kindness by giving you rain from heaven and crops in their seasons; he provides you with plenty of food and fills your hearts with joy (Acts 14.15-17 NIV). Paul and Barnabas were giving them the gospel (good news) because the common grace given to everyone wasn’t saving them. God gives testimony about Himself by sustaining the creation and its inhabitants. How many of these inhabitants turned to the God of Israel as a result of God’s kindness in common grace: none. Sure, there were Gentiles recorded in the O.T. who came to faith in the One True God, but they all came to faith as a result of “special grace,” that is, hearing the saving accounts of Israel’s God in history or responding to the providential preservation of His people..