It's all about His Righteousness

Romans 1-3 describes what we are by nature - condemned sinners with absolutely NO righteousness IN us.

Romans 3-5 describes what we receive when we become a Christian - Christ's righteousness ON us.

Romans 6-8 describes how to live as a Christian - with HIS righteousness IN us.

Romans 9-11 describes why God set Israel aside. In these chapters, we learn about God's righteousness WITH Israel.

Romans 12-15 describes how to actually SERVE God. We accomplish this with Christ's righteousness working THRU us.