Paul appears to take up the following issues/points:
The basic theme of the book is in 1:16-17 — the Gospel is the power of God for salvation to Jews and Gentiles (Greeks) — “he who through faith is righteous shall live.” (Hab 2:4)
1. The eschatological wrath of God is revealed against all sin and wickedness. (1:18-32)
2. God will judge both Jews and Gentiles without partiality, so “being a Jew” will not mean one will escape the wrath of God. (2:1-29) [In 2:13, he argues hypothetically that the doers of the Law will be justified, whether Jew or non-Jew. True “circumcision” is a matter of the heart, even a Gentile could presumably “keep the Law” and come out ahead of a Jew]
3. In fact, however, despite any advantage of Judaism, no one is righteous – neither Jew nor Gentile – all human beings are under the power of sin and are hopelessly lost. (3:1-30)
4. Justification comes by grace through faith based upon the sacrificial death/blood of Jesus Christ. There can be no human boasting. (3:21-31)
5. Abraham’s life illustrates this very point. He was justified by faith, before he was circumcised, and all who follow his way of “faith” are his heirs. (4:1-25)
6. Those justified by grace are not to continue in sin; they have become free of sin and death and have become “slaves” of righteousness. Through the Holy Spirit they “put to death” their sinful “flesh” and live in the Spirit. There is a constant struggle between the “flesh” and the “Spirit.” The problem is not the Law, which is good, holy and just, but rather sin working through the “flesh.” (chaps. 6 & 7)
7. Final redemption and cosmic victory will come. The elect will receive transformed, glorious bodies and creation itself will be set free from bondage to decay/mortality. (chap. 8)
8. Why has Israel, who is God’s chosen nation, largely not believed? Has God’s plan or promises failed? Absolutely not. A “remnant” of Israel is now being saved; the rest are “hardened” by God, who has turned to Gentiles to provoke his people to jealousy. Finally all Israel will repent. God is in control of all and all is working out according to His sovereign will. (chaps. 9-11)
Chapters 12 through 16 take up various ethical and practical exhortations.