The Roman church was deeply divided ethnically. Jews against gentiles. Gentiles against Jews. The Jews felt they were superior because they were Jews. The gentiles felt they were superior because they weren’t Jews. After all, hadn’t the Jews rejected Christ? Isn’t that why Jesus was put to death?
These ideas had some deleterious effects on the church in Rome. Jewish Christians, trusting in their heritage, were ignoring the lifestyle requirements of that heritage. Gentile Christians, rejecting Judaism altogether, rejected the lifestyle requirements of the law. Both were rejecting the Old Testament requirement of faith.
In chapter three, Paul sums up his point thus far: despite the great value of Jewish heritage, both Jews and gentiles stand alienated from God because of sin. The gap between them and God can be bridged by only one thing: faith in Christ Jesus.
But wait: it is actually two things – not made plain by the English text. First, there must be faith in Christ, specifically what he did on the cross in sacrificing himself for the sins of mankind. Do you believe that it is what Jesus did that reconciles you to God and not any merit you might possibly think you have with God? Answering “yes” to this question simply destroys the divisiveness of these self-righteous Christians.
Then, having lain all personal merit aside, there must be the faith of Christ, the faith Jesus had, living as Jesus lived.
There you have it: Paul’s point in Romans. Followers of Jesus must be totally dependent on what Christ has done for their relationship with God (called in this book “righteousness”). That dependence on God will lead them to live as God has directed in His law.