Paul’s letter would have made religious people uncomfortable. Abraham was seen to be the founder of the Israelite race and pattern of all to come. So is what Paul saying a total contradiction of the Old Testament? The two big guns are brought out to prove the point righteousness comes by faith not obey the Law. He uses Abraham and David.
Abraham believed God and it was counted to him as righteousness. And he did it before he was circumcised. The faith came first, resulting in him declared as righteous. The circumcision came later, so this is not just for circumcised Jews. Circumcision was a seal on what had happened. Much like baptism now.
The quote from David’s Psalm 32 is that the people who are blessed by God are notthose who have earned something from God, but those who have received something from Him. They are forgiven and covered! God accepts us through believing in him just as we are. We are granted a status of innocent that we have not earned or deserve.
It’s all pretty scandalous – we are let off the hook completely by Christ whose righteousness is given to us (imputed is the theological term). Jesus fulfilled the law in our place. It’s going to lead to the question in Romans 6:1 – can we continue in sin then? If our understanding of the grace doesn’t at least make us ask the question, then we haven’t yet grasped the enormity fo grace.
Allow that to marinate a couple of days until we find the answer to the question!