"Romans 2:6-7 refers to good works that belong to the moral sphere. The “works” that Paul speaks of in Romans 3:28 and Romans 4:5 refer to works that belonged to the Law of Moses, the keeping of which was necessary for Jews (circumcision, kosher laws, ritual washings, precepts governing the offering of sacrifices, etc.)."
Another pertinent text here would be 1 Timothy 1:8-10. Paul uses the term "Law" in a sense broader than boundary markers. In discussing their application, Paul pinpoints moral precepts as the "Law." That factor certainly weakens the distinction that some try to make between "works" and "works of the Law."
One more text worth discussing is Galatians 5:1-3. Circumcision was not part of the "moral sphere" of the Law, yet Paul said that those who seek after that ritual must obey it perfectly. That point blows the distinction made between "works" and "works of the Law" out of the water.
"The two verses immediately following Romans 3:28 bear this out. Right after juxtaposing the standards of faith and “works of law,” Paul writes in verse twenty-nine, “Is God the God of Jews only? Is he not the God of Gentiles also? Yes, of Gentiles also, since God is one.” This is the premise that leads Paul to the conclusion in the next verse that God will “justify the circumcised on the ground of their faith and the uncircumcised through their faith.” If Paul is juxtaposing faith and circumcision here in verse thirty, then we can conclude that circumcision is the kind of thing he has in mind when he juxtaposes faith with “works of law” in verse twenty-eight."
Paul does indeed juxtapose faith and circumcision, but it would nevertheless be a mistake to interpret "works of the Law" as referring exclusively to the ceremonial law. Both Jews and Gentiles ("circumcision" and "uncircumcision") are justified by faith, apart from the merit of any and all good works. That is the Apostle Paul's argument in Romans.
The Jewish people repeatedly violated the Mosaic Law. The Gentiles have rejected both conscience and the glory of God's creation. Consequently, both groups have incurred wrath and condemnation as a result of their unfaithfulness. Both Jews and Gentiles are saved by God's grace alone through faith alone.