The word ‘gospel’ means good news. Merely repeating the word without an understanding of what it signifies is to say nothing. What do we mean when we say that the gospel can do this or that? Paul here provides a definition of the gospel. He is not providing a slogan. A slogan is a kind of statement that entices a person in without saying everything that is important. In contrast, a definition is meant to highlight the important and cause the listener to think about the message.
What is the Christian gospel about? Paul says it is concerned with the righteousness of God, which must lead us to ask what the righteousness of God is. We can answer the question by saying that it is something that God is, it is something that God requires, and it is something that God provides. When we see the righteousness of God in these ways we will understand the gospel.
When we say that God is righteous, we mean that he is upright and opposed to sin, that he will not love, practice or tolerate unrighteousness. All he does, he does righteously and for his own glory. They are connected together, which is a reminder that anything that is not done for God’s glory is unrighteous.
Because God is perfect, he knows what righteousness is. Because God is sovereign, he requires righteousness from his subjects. If he does not insist on righteousness he would cease to be perfect. Because he is the judge of all his creatures, he will punish them for unrighteousness and reward them for righteousness. He has summarised his righteous requirements in the Ten Commandments, although we must remember that these requirements are not limited to a mere external conformity, as Paul himself had once imagined. The righteousness that God requires is constant and perfect conformity to his requirements. (Paul deals with our relationship to God’s law elsewhere in Romans, both as fallen creatures and as forgiven sinners, and explains in more detail several aspects of it.)
The problem we have with God’s righteousness is not that it is too demanding. It was not hard for Adam to keep God’s requirements before he disobeyed him in the Garden of Eden. It will not be hard for God’s redeemed people to keep God’s requirements in heaven. In the present, the problem we have as sinners is our inability to keep God’s requirements. We are responsible to keep them, but we cannot do so. Even worse, we do not even want to do so as sinners. But God continues to require us to do so.
The good news of the gospel is that the righteous God provides righteousness for the unrighteous. The righteousness that he provides was worked out by Jesus when he lived and died on earth. He obeyed the law for us and paid its penalty for us when on the cross. This righteousness is freely offered to us. It is a perfect righteousness that once received is ours forever.
How do we receive it? Paul tells us in this verse, by faith. There have been a variety of ways in which the phrase ‘from faith to faith’ has been interpreted. Some say it means that the righteous life is a life of faith, that it cannot be lived without faith in God (and Paul’s use of the phrase from Habakkuk that the just will live by faith would seem to agree with that interpretation). Others say that Paul means the harmony of faith found in Jews and Gentiles (it was first found in the Jews and then found in Gentiles, which is true, but may not be the truth intended here). Another view is that Paul is suggesting that the faith of each believer develops, becomes stronger, which again is true, but it is difficult to imagine Paul suggesting that a person with a strong faith is more righteous than a person with weak faith – we are classified as righteous not because of the strength of our faith but because of the Object of our faith, Jesus. So I would suggest that the phrase means that the righteous live by faith in Christ, which is the message of the Book of Romans.