Undoubtedly, the one passage in Romans that doesn’t seem to “fit” the
standard Reformation explanations of both gospel and justification is
found in Romans 2 and I am clipping a few verses to set our next use of
“gospel” in context:

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. 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 since they show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts now accusing, now even defending them.) 16 This will take place on the day when God will judge men’s secrets through Jesus Christ, as my gospel declares.

Our concern is down in verse 16: Paul declares that God’s judgment will be based in several factors – Jesus Christ, the law, and the gospel.  The Greek text here reads like this: “on the Day when God will judge the secrets of humans according to my gospel through Jesus Christ.” Scholars have not been able to determine convincingly what this expression means with clarity. What is clear is this: God will judge; God will judge according the Torah; God will judge through Jesus Christ – and this is all a part of Paul’s own gospel. In other words, the final judgment factors into what Paul means by “gospel.”