Know then that it is those of faith who are the sons of Abraham. And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, "In you shall all the nations be blessed." So then, those who are of faith are blessed along with Abraham, the man of faith. (Galatians 3:7-9 ESV)
You foolish Galatians, who has bewitched you, before whose eyes Jesus Christ was publicly portrayed as crucified? This is the only thing I want to find out from you: did you receive the Spirit by the works of the Law, or by hearing with faith? Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh? (Galatians 3:1-3 NASB)
I have been crucified with Christ. It is no longer I who live, but 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. I do not nullify the grace of God, for if righteousness were through the law, then Christ died for no purpose. (Galatians 2:20-21 ESV)
But when Cephas came to Antioch, I opposed him to his face, because he stood condemned. For before certain men came from James, he was eating with the Gentiles; but when they came he drew back and separated himself, fearing the circumcision party. And the rest of the Jews acted hypocritically along with him, so that even Barnabas was led astray by their hypocrisy. But when I saw that their conduct was not in step 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 force the Gentiles to live like Jews?"
But not even Titus, who was with me, though he was a Greek, was compelled to be circumcised. But it was because of the false brethren secretly brought in, who had sneaked in to spy out our liberty which we have in Christ Jesus, in order to bring us into bondage. But we did not yield in subjection to them for even an hour, so that the truth of the gospel would remain with you.
My soul clings to the dust;
And I was still unknown in person to the churches of Judea that are in Christ. They only were hearing it said, "He who used to persecute us is now preaching the faith he once tried to destroy." And they glorified God because of me. (Galatians 1:22-24 ESV)
For am I now seeking the favor of men, or of God? Or am I striving to please men? If I were still trying to please men, I would not be a bond-servant of Christ. (Galatians 1:10 NASB)
I am astonished that you are so quickly deserting him who called you in the grace of Christ and are turning to a different gospel - not that there is another one, but there are some who trouble you and want to distort the gospel of Christ. (Galatians 1:6-7 ESV)