Romans 4 is an important key to the rest of the book. Paul expounds at length on Abraham’s experience of justification by faith apart from works. He also calls Abraham “the father of the circumcised who not only are circumcised but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised” (4:12). Abraham is the father of those who live their faith. Faith is not only a confession, it is a way of life.
What is crystal clear in Paul ’s exposition is that the favored status of Abraham and his descendants rested not on their keeping of the law, but on the promise. “It was not through law that Abraham and his offspring received the promise that he would be heir of the world, but through the righteousness that comes by faith. For if those who live by law are heirs, faith has no value and the promise is worthless, ... Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham's offspring—not only to those who are of the law but also to those who are of the faith of Abraham. He is the father of us all” (4:13-16).
In Galatians Paul premises the covenant on the promise even more explicitly. “What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise. For if the inheritance depends on the law, then it no longer depends on a promise; but God in his grace gave it to Abraham through a promise” (Gal 3:17-18). The covenant which Paul is here extending to all those who follow in the footsteps of Abraham is based not on the Law or law-keeping, but on the Promise made by God with no consideration whatsoever for any worthy action on the part of Abraham and his descendants. This is not to say there were no expectations of Abraham and the Israelites. The iterations of the covenants are laced with entreaties to obey God and walk in His ways (Deut 6), and some of the benefits of the covenant were linked to obedience (Lev 26, Deut 28), but the promise was extended solely by the grace of God.
Then Paul links the righteousness attributed to Abraham with the righteousness attributed to us who believe in Jesus (4:24). We are reconciled without regard to our merit by the death of Christ who died for the ungodly, for us who are sinners, and how much more shall we be saved through the resurrection life of Christ! (5:9,10). Paul frequently gets side-tracked in his enthusiasm. He begins exultantly “Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all men, because all sinned” (5:12) and then he digresses for a while “for before the law was given, sin was in the world. But sin is not taken into account when there is no law. Nevertheless, death reigned from the time of Adam to the time of Moses, even over those who did not sin by breaking a command, as did Adam, who was a pattern of the one to come” (5:13-14). Evidently he was going to draw a comparison (indicated by the use of “just as”) that got lost. Nevertheless, he gets back on track, and the comparison turns out to be not only a simple comparison, but a comparison of superlative. “But the gift is not like the trespass. For if the many died by the trespass of the one man, how much more did God's grace and the gift that came by the grace of the one man, Jesus Christ, overflow to the many! Again, the gift of God is not like the result of the one man's sin: The judgment followed one sin and brought condemnation, but the gift followed many trespasses and brought justification. For if, by the trespass of the one man, death reigned through that one man, how much more will those who receive God's abundant provision of grace and of the gift of righteousness reign in life through the one man, Jesus Christ” (5:15-17). While there is a comparison in how we all sinned in Adam, and are all made righteous in Jesus, the comparison is not strictly equal. The gift is far greater than the trespass. “For if the many died by the trespass of the one man, how much more did God's grace and the gift that came by the grace of the one man, Jesus Christ, overflow to the many!” The parallelism in terminology makes it clear that the many who died in Adam are superlatively the recipients of the grace and gift of God through Jesus Christ! Lest there be any misunderstanding Paul reiterates “Consequently, just as the result of one trespass was condemnation for all men, so also the result of one act of righteousness was justification that brings life for all men” (5:18). If one trespass brought death for all, Christ’s one act of righteousness superlatively brings life for all. Again, to emphasize “For just as through the disobedience of the one man the many were made sinners, so also through the obedience of the one man the many will be made righteous” (5:19). The parallelism is unmistakable - those who sinned in Adam are restored in Jesus. There is no hint here of any difference in the extent of the curse in Adam and the extent of the blessing in Christ. The only difference Paul allows is that whatever happened in Adam is more than reversed in Christ.
However, lest anyone mistake this as a free ticket to sin more so that grace would also increase, Paul emphatically declares “What shall we say, then? Shall we go on sinning so that grace may increase? By no means! We died to sin; how can we live in it any longer? Or don't you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life” (6:1-4). We should consider ourselves dead to sin, because that is what the gift means. We have been given an incredible gift but we must beware squandering this gift by returning to our old ways for “the wages of sin is death” (6:23). That Paul is under no illusion about the reality of the struggles we continue to face is reflected in his confession “I do not understand what I do. For what I want to do I do not do, but what I hate I do. And if I do what I do not want to do, I agree that the law is good. As it is, it is no longer I myself who do it, but it is sin living in me. I know that nothing good lives in me, that is, in my sinful nature. For I have the desire to do what is good, but I cannot carry it out. For what I do is not the good I want to do; no, the evil I do not want to do—this I keep on doing. Now if I do what I do not want to do, it is no longer I who do it, but it is sin living in me that does it. So I find this law at work: When I want to do good, evil is right there with me. For in my inner being I delight in God's law; but I see another law at work in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin at work within my members. What a wretched man I am! Who will rescue me from this body of death? Thanks be to God—through Jesus Christ our Lord! So then, I myself in my mind am a slave to God's law, but in the sinful nature a slave to the law of sin” (7:15-25). Paul experienced excruciating disappointments in his inability to live according to his deepest desires to do good, and found himself time and again doing the very things he did not want to do. Paul was a saint, but he was a real saint who lived a real life engaged in the daily struggle to live the life of Christ in his flesh.
Paul continues with the life we live through the Spirit. It is an incredible opportunity, but it is also an obligation (8:12). It is something that is given to us, but it is also something we must choose, not just by an intellectual assent, but also by a way of life (8:13). Our choice is not simply a decision, it is a life. We, and all of creation, waits in eager expectation for liberation from our bondage to decay (8:19-20). And we know that God is always working for our good (8:28). In fact, God does everything required for us, and with God on our side, it matters not who is against us (8:29-32). We are God’s, and nothing can ever separate us from the love of God that is in Christ Jesus our Lord (8:37-39).