Righteousness is counted on the basis of faith. Paul makes this point and sets the theme of his letter when he writes: “I am not ashamed of the good news; it is, in fact, God’s power for salvation to everyone having faith, to the Jew first and also to the Greek; for in it God’s righteousness is being revealed by reason of faith and toward faith, just as it is written: ‘But the righteous one​—by means of faith he will live.’”​—Romans 1:16, 17.

In Romans chapter 1 through chapter 4, Paul begins with the truth that everyone is guilty of sin. Hence, the only way that humans can be declared righteous is on the basis of faith. True, the Jews tried to be righteous by keeping the Mosaic Law. But they failed. Hence, Paul boldly says: “Jews as well as Greeks are all under sin.” He proves this unpopular truth with a number of Scripture quotations.​—Romans 3:9.

Since “by works of law no flesh will be declared righteous,” what hope is there? God will declare humans righteous as a free gift on the basis of Jesus’ ransom sacrifice. (Romans 3:20, 24) To avail themselves of this, they must have faith in that sacrifice. Is this teaching that humans are declared righteous on the basis of faith something novel? Not at all. Abraham himself was declared righteous because of his faith before the Law was even inaugurated.​—Romans 4:3.

Having established the importance of faith, Paul in chapter 5 discusses the basis of Christian faith. This is Jesus, whose course of righteousness annuls the bad effects of Adam’s sin for those who have faith in Him. Thus, “through one act of justification,” not by obeying the Mosaic Law, “the result to men of all sorts is a declaring of them righteous for life.”​—Romans 5:18.