Ephesians 2:8-9 have had an immense impact on the history of Christianity these last five hundred years because these are some of the key verses of the Protestant Reformation: “by grace you have been saved, through faith—and this not from yourselves, it is the gift of God—not by works, so that no one can boast.” Interpreters of Paul ever since have had a tendency to read Paul’s earlier letters through the lens of these verses. But there are some key distinctions between Ephesians 2:8-9 and letters like Romans and Galatians. It is actually Ephesians that is unusual for Paul.
For example, Paul does not usually speak of salvation in the past tense: “you have been saved.” Romans 5:9 speaks of how we will be saved from God’s wrath, namely, on the Day of Wrath which is to come. Salvation is thus something that has not yet happened literally. Even in Ephesians, “you have been saved” probably is a poetic way of saying that it is a sure thing. Because of God’s grace, because of the audience’s faith, their salvation is going to happen at the appropriate time.
A second difference is in what “works” are in mind. In Galatians and Romans, the works Paul has in mind are works of the Jewish Law. Paul may be writing to Gentiles, but he is defending his preaching in the light of objections from other Jewish believers. His basic message is that no one can be right with God by how well they keep the particulars of the Jewish Law, especially the parts that most distinguished Jew from Gentile: circumcision, food laws, Sabbath observance, and so forth.
But Ephesians is not a defense against Jewish opposition. Ephesians only uses the word “law” once, and there only to say that Christ has abolished it—also quite unlike Romans, as we will see below. So when Ephesians 2:9 says that its audience is not saved by works, it is saying something quite different from Romans 3:28. The works in question are not works of the Jewish Law, but good works in general. While Romans says that a Jew does not have an advantage before God because of the Jewish Law, Ephesians says that no one is good enough to escape God’s wrath.
Interestingly, Ephesians is accordingly more positive toward works once one is "saved." We are "created in Christ Jesus to do good works" (Eph. 2:10). In Romans and Galatians, works of law are something a Gentile believer should not do. Indeed, Paul tells the Galatians that if they become circumcised, Christ will be of no use to them (Gal. 5:2). So works of Law are something a believer should not do, at least not a Gentile believer. In Ephesians, by contrast, good works are a good thing. They cannot save a person from God's wrath, but they are something God has created us to do in the name of Christ.