14 (Indeed, when Gentiles, who do not have the law, do by nature things required by the law, they are a law for themselves, even though they do not have the law. 15 They show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts sometimes accusing them and at other times even defending them.)
While the above two verses are parenthetical, only the NIV, NCV, and the ARS saw fit to literally place them inside parentheses. Ellicott’s Commentary, written well before the 20th century actually says
A sort of parenthesis begins here. Romans 2:16 refers back to the main subject of the paragraph, and not to the particular point on which the Apostle digresses in Romans 2:14-15, the virtual operation of law among the Gentiles as well as Jews.
I would disagree slightly with Ellicott’s statement about 2:16 for while it does refer back to the main subject, it is also applicable to the verses we have before us today. So let’s look at the two preceding verses and 2:16 to see for ourselves.
12 All who sin apart from the law will also perish apart from the law, and all who sin under the law will be judged by the law. 13 For it is not those who hear the law who are righteous in God’s sight, but it is those who obey the law who will be declared righteous.
16 This will take place on the day when God judges people’s secrets through Jesus Christ, as my gospel declares.
It is obvious verse 16 applies to both those who have the law, the Jews, and those who do not have the law, the Gentiles. This brings us back to our verses of the day with the explanation of why Gentiles do by nature things required by the law even though they do not have the law.
Why is this, how can it be? It is because the requirements of the law are written on their hearts. Paul provides this truth in a different context in 1:20 of this book
For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse.
Thus no individual has an excuse. God’s eternal power and divine nature have been known by each of us and further the requirements of the law are written on our hearts. We know, in our heart of hearts what is right and what is wrong. There can be no excuse, but there can be forgiveness before the day when God judges people’s secrets through Jesus Christ, as my [Paul’s] gospel declares. Paul states this very clearly in chapter one
16 For I am not ashamed of the gospel, because it is the power of God that brings salvation to everyone who believes: first to the Jew, then to the Gentile. 17 For in the gospel the righteousness of God is revealed—a righteousness that is by faith from first to last just as it is written: “The righteous will live by faith.”
Paul will get around to saying directly how this is accomplished in chapter ten with reference to our hearts once again.
9 If you declare with your mouth, “Jesus is Lord,” and believe in your heart that God raised Him from the dead, you will be saved. 10 For it is with your heart that you believe and are justified, and it is with your mouth that you profess your faith and are saved.
It is wonderful to know we have the Free Gift of Grace through Jesus if we will but declare Jesus is Lord and believe in our hearts that God raised Him from the dead.