What does Romans 1:17 mean?

This, together with the previous verse, is often referred to as the central theme of the book of Romans. Paul has declared boldly that he is not ashamed of the gospel. Why? It is the power of God for salvation to everyone who believes (Romans 1:16).

Now Paul describes what the gospel does. In the gospel, the righteousness of God is "revealed," in one sense, in that it is given to human beings by their faith in Christ. In other words, God declares human beings to be righteous in His eyes because of their faith. The words "from faith to faith" likely mean that this declaration of people being righteous is by faith from first to last, from start to finish.

As Romans will make abundantly clear, people cannot be declared righteous before God by following the law. Good works and ritual obedience do nothing to make us right with God. And if we are not declared righteous in God's eyes—a condition referred to as being "justified"—then we cannot be with God. We are separated from Him forever because of our sinfulness. However, according to the gospel, Christ died to pay the penalty of death and separation from God for our sins on the cross. When we trust in Christ, God sees us through Christ and declares us to be "righteous" or "justified."

Paul put the same idea this way in Philippians 3:8–9: "that I may gain Christ and be found in him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ, the righteousness from God that depends on faith."

This is God's gospel: God's "good news" for humanity. Paul quotes Habakkuk 2:4 to show this is not a new idea: "The righteous shall live by his faith."