Paul gave a succinct summary of the gospel in Romans 3:23-24: “for all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus.” Paul understood that sin is universal. Likewise, everyone deserves God’s judgment because everyone is a sinner, and God is right to be angry with them. Everyone should know better. Gentiles who have never heard of God know enough about him through creation to be without excuse, and Jews have heard God’s will through his law. But merely knowing the law or outwardly observing it will not save Jews from God’s wrath. Only God can bring about salvation, and he did so by sacrificing his Son on the cross, taking our sin upon himself and justifying us through his righteousness. This righteousness can only be gained by faith.
Paul also understood that the gospel has the power to change everything. He said in 8:1-2, “There is therefore now no condemnation for those who are in Christ Jesus. For the law of the Spirit of life has set you free in Christ Jesus from the law of sin and death.” There is power in the gospel to reconcile us to God, to give us peace with God, and to break the chains of sin and death. The law can no longer convict us because we are dead to sin and made alive in Christ. We will still struggle with sin in this life, but as Paul said in 6:14, “For sin will have no dominion over you, since you are not under law but under grace.”
A key concern of the early church was the relationship between the Old Testament law and the New Testament gospel and the corresponding relationship between the people of the old covenant and the people of the new covenant. Paul addressed these concerns by showing that the Jews, as well as the Gentiles, relied on God’s grace for their salvation. As Paul put it in 11:32, “For God has consigned all to disobedience, that he may have mercy on all.” Paul made clear that God’s saving grace is not limited by national or ethnic boundaries. Rather, it depends on God’s sovereign choice, so that God can say to Moses, “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion” (Rom. 9:15).
Paul also made a point of showing that the free grace of the gospel could never result in complacent Christians. Rather, God’s grace transforms the lives of the people it touches, and as the Heidelberg Catechism Q&A 1 puts it, “he makes us wholeheartedly ready and willing from now on to live for him.” For Paul, Christians are not only justified (made right with God) by God’s grace, but they are also sanctified (made more and more holy each day) by his grace. He said in 12:1, “I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice acceptable to God, which is your spiritual worship.
(Excerpt from The Books of the New Testament, pp. 54-5)