Paul reminds the Galatians of the nature of the Gospel he preaches and teaches. The Good News he freely shares, wherever he goes, came directly from Jesus Christ. Paul did not receive it from any human being. His calling, by the grace of God, is to take the Gospel to the world of the Gentiles even as Peter has a calling to share the Good News with the Jews. And that calling and Gospel were confirmed when Paul met with the leaders in Jerusalem; James, Peter, and John.
Circumcision, while a sign of the Old Covenant/Testament, was not required for followers of Jesus in the Gentile world. The essential Gospel is about Jesus Christ and not Old Testament rules and regulations such as circumcision. On this both the Jewish Christian Leaders in Jerusalem and Paul were in agreement. See Acts 15:1-32 on the Jerusalem Council where this was decided.
How wonderful to see that they understood the essential message of the grace of Jesus Christ when they took the Gospel into all the world. How wonderful to see the church so eager to reach out beyond Israel to all the world. May we find joy in the essential Gospel; that is the grace, love, hope, and peace of God given to us in the person and presence of Jesus. And may we also find joy in sharing this extraordinary news and love of Christ in our own world today. What could be more essential?