I was doing some writing on the topic of justification today, and I noticed something about the times Paul says we're justified by grace through faith. Here are the passages I have in mind, which I'll abridge to highlight what I noticed:
But now, irrespective of law, the righteousness of God has been disclosed... the righteousness of God through faithfulness to Jesus Christ*232425282930 for all who believe. For there is no distinction... they are now justified by his grace as a gift, through the redemption that is in Christ Jesus... Then what becomes of boasting [of being Jewish]? It is excluded. By what law? By that of works? No, but by the law of faithfulness. For we hold that a person is justified by faithfulness apart from works prescribed by the Torah. Or is God the God of Jews only? Is he not the God of Gentiles also? Yes, of Gentiles also, since God is one; and he will justify the circumcised on the ground of faithfulness and the uncircumcised through that same faithfulness.
For the promise that he would inherit the world did not come to Abraham or to his descendants through the Torah but through the righteousness of faith. If it is [only] the adherents of the Torah who are to be the heirs, faithfulness is null and the promise is void... For this reason it depends on faithfulness, in order that the promise may rest on grace and be guaranteed to all his descendants, not only to the adherents of the Torah but also to those who share the faithfulness of Abraham...2345
You [Gentiles] were dead through the trespasses and sins in which you once lived... But God, who is rich in mercy... made us alive together with Christ*678910—by grace you have been saved— and raised us up with him and seated us with him in the heavenly places in Christ Jesus, so that in the ages to come he might show the immeasurable riches of his grace in kindness towards us in Christ Jesus. For by grace you have been saved through faithfulness, and this [grace] is not your own doing; it is the gift of God— not the result of works [of the Torah], so that no one may boast [because of their Jewishness - see Rom 3:21-30]... So then, remember that at one time you Gentiles by birth... were at that time without Christ, being aliens from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ. For he is our peace; in his flesh he has made both groups into one and has broken down the dividing wall, that is, the hostility between us. He has abolished the law with its commandments and ordinances, so that he might create in himself one new humanity in place of the two, thus making peace, and might reconcile both groups to God in one body through the cross, thus putting to death that hostility through it.
What I noticed is this: Paul speaks of being justified by grace through faithfulness in the context of emphasizing that God accepts Gentiles as his people too. The common Jewish belief at the turn of the first century was that only Jews were God's people, and that Gentiles could not be - as least without fully following the Jewish way of life, their Torah. Following Jesus, though, Paul says that God will not judge people based on their Jewishness but based on whether they are faithful to live in a godly way like Jesus taught and exemplified. Paul saw the highly controversial implication - people who did not follow the Torah could be considered righteous by God. In other words, God did not limit his favour (aka. "grace") to the Jews, but also extended it to the Gentiles. This is why Paul talks of grace in the context of justification and the inclusion of the Gentiles as people whom God considers righteous.
For Paul, the boundless favour of both God and Jesus was evident in the activity of Jesus, who revealed a way for both Jews and Gentiles to be saved from sinfulness, and thus be considered righteous before God. I do not have time here to explain why I have emphasised that this salvation was from sinfulness, as opposed to something else. (Perhaps that is the topic of another post.) It was truly gracious of God to commission Jesus to save sinful Jews from their unrighteousness, but this grace even extended to Gentiles also. The inclusiveness of God's grace was the point that Paul laboured, and the very issue that got him in so much trouble with the Jews who zealously protected their exclusive claim as God's people.