11But when Cephas came to Antioch, I opposed him to his face, because he stood self-condemned; 12for until certain people came from James, he used to eat with the Gentiles. But after they came, he drew back and kept himself separate for fear of the circumcision faction. 13And the other Jews joined him in this hypocrisy, so that even Barnabas was led astray by their hypocrisy. 14But when I saw that they were not acting consistently with the truth of the gospel, I said to Cephas before them all, “If you, though a Jew, live like a Gentile and not like a Jew, how can you compel the Gentiles to live like Jews?”
15We ourselves are Jews by birth and not Gentile sinners; 16yet we know that a person is justified not by the works of the law but through faith in Jesus Christ. And we have come to believe in Christ Jesus, so that we might be justified by faith in Christ, and not by doing the works of the law, because no one will be justified by the works of the law. 17But if, in our effort to be justified in Christ, we ourselves have been found to be sinners, is Christ then a servant of sin? Certainly not! 18But if I build up again the very things that I once tore down, then I demonstrate that I am a transgressor. 19For through the law I died to the law, so that I might live to God. I have been crucified with Christ; 20and it is no longer I who live, but it is Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me. 21I do not nullify the grace of God; for if justification comes through the law, then Christ died for nothing.
Apostle Paul's intense commitment to the gospel of Jesus Christ, at times, made him an unfriendly person. The leader of the Jesus movement after Jesus' death and resurrection was the Apostle Peter. Peter was one of three closest to Jesus while He walked on earth (the other two, John and James). Peter became the de facto leader of the Jerusalem Church, which was the center of Hebraic Christianity. As such, Jewish identity and Jewish ways were of great importance in following Yeshua. For these early leaders, "Christianity" could not be imagined or understood without Jewish requirements, including circumcision for men who desired to follow Yeshua the Messiah. So when Peter (Cephas) waffled on the question of circumcision, Paul had no problem telling it like it is, opposing Peter "to his face."
From Paul's perspective (as he was informed by the Resurrected Christ), such ritual requirement nullified the full grace of God's acceptance of sinners in the gospel of Jesus Christ. Such requirement smacked of "works-righteousness" or "works of the law." This notion of "works-righteousness" or "works of the law" is easy to understand: that our acceptance by the holy and righteous God is based wholly or in part on our doing something. Becoming religiously Jewish, fulfilling some ritual requirement, saying some special prayer, going on a holy pilgrimage, undertaking a fast, giving alms, and so forth. Anything we do to contribute to our salvation is "works." From the gospel's perspective, no work is good enough. That's not saying it quite right. It's not as if there is some "work" out there that might be good enough. "Good enough" simply does not apply. "Work" and "grace," we can say, are categorically different, like the color blue and fried chicken.
The gospel of Jesus Christ is God's gracious acceptance of us based on the life, death, and resurrection of God's Son, Jesus the Messiah. Our role? To receive God's gracious gift by saying Yes to Jesus and following Him with all our being for all our days. The gift of new life in Christ cannot be pictured as something you receive at some point in time and then you forget or walk away from. It's not like getting a package from the UPS guy and leaving the package somewhere in the house. It's more like getting married or enlisting in the Marines or enrolling in graduate school. It's saying yes to a certain type of commitment and following through.
That's why, for Paul, the gospel of Jesus Christ means a different way of living, made possible only by Christ Himself: I have been crucified with Christ; and it is no longer I who live, but it is Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me.
The gospel of Jesus begins with our acceptance of the Gift and then this Gift (Person) takes over, in a good way.
Let's pray: Lord Jesus, we thank you for the Gospel, the Good News, of justification -- the divine acceptance of us as sinners who are forgiven and who are becoming renewed and redeemed. We thank you for the good news of new life in God, that our days are now infused with your love and presence for all eternity. We thank you for the freedom from the burden of "works," that we need not worry about how to please you by impressing you with how good we are. We can simply BE who we are in You and find peace. We thank you for your complete acceptance and love. In Your Name, Amen.