Paul was last speaking on sowing and reaping. He continued with his concluding remarks.
Galatians 6:11-18 (KJV)
Ye see how large a letter I have written unto you with mine own hand.
As many as desire to make a fair shew in the flesh, they constrain you to be circumcised; only lest they should suffer persecution for the cross of Christ.
For neither they themselves who are circumcised keep the law; but desire to have you circumcised, that they may glory in your flesh.
But God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world.
For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature.
And as many as walk according to this rule, peace be on them, and mercy, and upon the Israel of God.
From henceforth let no man trouble me: for I bear in my body the marks of the Lord Jesus.
Brethren, the grace of our Lord Jesus Christ be with your spirit. Amen.
In New Testament times, the Biblical writers often used professional scribes to put their writings into the most clear yet space-saving format as possible. Paul wrote his conclusion in his own hand in a much larger print than the small, neat writing that the scribe used in the rest of Paul's letter (verse 11). This also served as an authentication of his work.
The false teachers had come to the Galatian assembly trying to make a good impression that would sway the new believers (verse 12). But Paul believed that the false teachers' reason for compelling the Galatian believers to be circumcised and ritually become Jews was so that persecution for the cross of Messiah would be avoided. They wanted to believe in Messiah Yeshua, but continue to fit in with traditional Judaism. However, Paul pointed out in verse 13 that the false teachers were not in obedience to Torah, because they insisted that a man-made act of ritual would make someone a Jew, when Torah was clear that salvation came by grace through faith. The only thing that the ritual would accomplish was that the false teachers could boast about their flesh.
But Paul would never boast about anything except the cross of Messiah Yeshua, which "crucified" the world to Paul and he to the world (verse 14). Being a Jew or a Gentile was not what was important, but becoming a new creation in Messiah was (verse 15).
Paul then gave a benediction of peace and mercy over those Galatians who lived according to this rule (of being a new creation in Messiah) and to all Israel of God (verse16). By using the phrase, "Israel of God," Paul confirmed that God's people, whether Jew or Gentile, are called collectively, Israel.
Verses 17 and 18 finish Paul's remarks. He had made his case and that was enough. He needed to vindicate his actions and beliefs no further since he bore in his body the evidence (scars of persecution) of a life lived for Yeshua. He ended his benediction by addressing the Galatian brethren, asking God to give them the grace of Messiah Yeshua.