Our verses for today begin in chapter 4, verses 1-8, but we need to look back into chapter 3, verses 28-31 to get the context:

In these verses and those immediately preceding our verses for today, Paul has made a shocking declaration: Obedience to God's law does not make a person justified...even perfect obedience would not give us a right standing before Him, because we were born sinners.

Obedience to the law is concerned with what a man can do for himself; the way of grace is concerned with what God has done to win for us His forgiveness; nothing we can ever do can win for us the forgiveness of God; therefore the way to a right relationship with God lies, not in a frenzied, desperate, doomed attempt to win acquittal by our performance; God has already done everything necessary to allow us to stand boldly before Him, not on the basis of what we have done, but solely on the basis of what Jesus Christ has done for us. Our only possible response lies in the humble, penitent acceptance of the love and grace which God offers us in Jesus Christ.

If the way to God is the way of faith and of acceptance, then all boasting in human achievement is gone. There was a certain kind of Judaism which kept a kind of profit and loss account with God. In the end a man often came to a frame of mind in which he believed that God was in his debt. That same frame of mind exists today among certain Christians. Paul’s position was that every man is a sinner and God’s debtor and no man could ever put himself back into a right relationship with God through his own efforts and that grounds for self-satisfaction and boasting in one’s own achievement no longer exist.

And to the Jews who might argue that God's grace might be alright for the Gentiles who never knew the law, but certainly He expected those to whom He gave the law to obey it, Paul directs them to the one sentence that is foundational in the Jewish creed...it's the sentence that began every synagogue service and still does today: "Hear, O Israel, the Lord our God is one God." (Deuteronomy 6:4)  There is not one God for the Gentiles and another for the Jews!  God is one!  The way to God is the same for both Gentiles and Jews...it is not the way of human achievement; it is the way of trusting and accepting by faith.

If a Jew asked this question: "Since both Jews and Gentiles are saved apart from the law, does that mean the law is no longer needed?", it would be easy to assume that Paul's answer would be "Yes", but verse 31 makes it clear that his answer is "No".

Paul uses the word "law" 78 times in the NASB95 translation of Romans and 140 times in all his epistles. If you want to understand Paul's position regarding God's law, you need to read all he says on the subject, because, on the surface, it can appear that he sees no continuing use for the law.

Here are some examples often quoted to prove that Paul believed that the law was done away with...nailed to the cross:

For we maintain that a man is justified by faith apart from works of the law. (Romans 3:28)

But if the ministry of death, in letters engraved on stones, came with glory, so that the sons of Israel could not look intently at the face of Moses because of the glory of his face, fading as it was, how will the ministry of the Spirit fail to be even more with glory? For if the ministry of condemnation has glory, much more does the ministry of righteousness abound in glory. For indeed what had glory, in this case has no glory because of the glory that surpasses it. (2Corinthians 3:7-10) 

For as many as are of the works of the Law are under a curse; for it is written, "Cursed is everyone who does not abide by all things written in the book of the law, to perform them." Now that no one is justified by the Law before God is evident; for, "The righteous man shall live by faith." However, the Law is not of faith; on the contrary, "He who practices them shall live by them." Christ redeemed us from the curse of the Law, having become a curse for us—for it is written, "Cursed is everyone who hangs on a tree"—in order that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we would receive the promise of the Spirit through faith. (Galatians 3:10-14)

But here are some examples that make it clear that Paul understood the proper place of the law, even after the cross: 

Do we then nullify the Law through faith? May it never be! On the contrary, we establish the Law. (Romans 3:31)

Is the Law then contrary to the promises of God? May it never be! For if a law had been given which was able to impart life, then righteousness would indeed have been based on law. But the Scripture has shut up everyone under sin, so that the promise by faith in Jesus Christ might be given to those who believe. But before faith came, we were kept in custody under the law, being shut up to the faith which was later to be revealed. Therefore the Law has become our tutor to lead us to Christ, so that we may be justified by faith. But now that faith has come, we are no longer under a tutor. (Galatians 3:21-25)

But we know that the Law is good, if one uses it lawfully, realizing the fact that law is not made for a righteous person, but for those who are lawless and rebellious... (1Timothy 1:8-9)

The Jews regarded Abraham as the great founder of the race and the pattern of all that a man should be. Paul has just been seeking to prove that what makes a man right with God is not the performance of the works that the law lays down, but the simple trust which takes God at His word and believes that He still loves us even when we have done nothing to deserve that love. The immediate reaction of the Jews was one of incredulity...what Paul was teaching seemed to contradict everything they had believed about having a right relationship with God.  But Paul contends that instead of being some new theological novelty, his gospel of grace and faith are the very foundations of the Jewish religion and he uses Abraham to prove it. The ordinary mind finds abstract ideas hard to grasp, so a wise teacher, and Paul was certainly that, links the abstract idea of faith to a person...Abraham.  He in essence was saying, "Here's what faith looks like in action."

Now the story of Abraham was well known among the Jews, even hundreds of years later, because they had faithfully passed down by oral tradition the account of God appearing to Abram and telling him to leave his homeland and family to go into a place that God would show him and He would make of Abram a great nation. It was not that Abraham meticulously performed the demands of the law that put him into his special relationship with God, but his complete trust in God and his complete willingness to abandon his life to God. 

And truthfully, Abraham didn't do all that great many times in his life...twice he lied about his wife and gave her to another man to save his own life; he argued with God about the destruction of Sodom and Gomorrah; and he conspired with Sarah to "help God out" by producing a son with Hagar.  Not until he offered Isaac as a sacrifice did Abraham truly, without hesitation, demonstrate his faith in God.

The story of Abraham, like most historical events, with the passage of time, gets distorted.  That process is called revision...the truth of the historical event gets "revised" to fit the agenda of the "historian" who makes the revision

A few of the more advanced Rabbis still believed that Abraham's special relationship with God was based solely upon faith.  One rabbinic commentary said, "Abraham, our father, inherited this world and the world to come solely by the merit of faith whereby he believed in the Lord; for it is said, 'And he believed in the Lord, and He accounted it to him for righteousness.'"

The great majority, however, had turned the Abraham story to suit their own beliefs. They held that because he was the only righteous man of his generation, therefore he was chosen to be the ancestor of God’s special people. The immediate question is, "But how could Abraham keep the law when he lived hundreds of years before it was given?" These Rabbis advanced the odd theory that he kept it by intuition or anticipation. "At that time," says the Apocalypse of Baruch, "the unwritten law was named among them, and the works of the commandment were then fulfilled." "He kept the law of the Most High," says Ecclesiasticus, "and was taken into covenant with God. … Therefore God assured him by an oath that the nations should be blessed in his seed."

The Rabbis were so in love with their theory of works that they insisted that it was because of his works that Abraham was chosen, although it meant that they had to argue that he knew the law by anticipation, since it had not yet come. This distortion was not restricted to the Rabbis alone, even James, in his epistle, contended that Abraham was declared righteous by his obedience, not by faith alone. Here's what he says in chapter 2:21-24: Was not Abraham our father justified by works when he offered up Isaac his son on the altar? You see that faith was working with his works, and as a result of the works, faith was perfected; and the Scripture was fulfilled which says, "And Abraham believed God, and it was reckoned to him as righteousness," and he was called the friend of God. You see that a man is justified by works and not by faith alone.  

Paul further buttresses his argument that all humans are declared righteous by God, by quoting David, albeit not verbatim, from Psalm 32:1-2: How blessed is he whose transgression is forgiven, whose sin is covered! How blessed is the man to whom the Lord does not impute iniquity, and in whose spirit there is no deceit!

Paul's quote reads: Blessed are those whose lawless deeds have been forgiven, and whose sins have been covered. Blessed is the man whose sin the Lord will not take into account.

The words will not take into account are not found in the Psalm quotation and seem to be a reference to 2Corinthians 5:18-21: Now all these things are from God, who reconciled us to Himself through Christ and gave us the ministry of reconciliation, namely, that God was in Christ reconciling the world to Himself, not counting their trespasses against them, and He has committed to us the word of reconciliation. Therefore, we are ambassadors for Christ, as though God were making an appeal through us; we beg you on behalf of Christ, be reconciled to God. He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him.

We need to be careful that we don't fall into the trap of substituting our faith for our works, thereby making faith another form of works.  God's declaration that all humans are counted as righteous is not conditioned on faith or works.  It is an historical fact!  The faith that believes and trusts God is not human faith, it is the faith given to the believer by God.  Paul makes that clear in Galatians 2:20: I no longer live, but Christ lives in me, and the life that I now live in the flesh I live by the faithfulness of the Son of God, who loved me and gave himself for me. Our focus must always be on Jesus, both for salvation and for living!