The Gospel or No Gospel

Several years ago, a Gentile friend began attending a Jewish fellowship which embraced the Lord Jesus as the Messiah. He told me he was going to get circumcised so he could be closer to God. How would you respond to this? Galatians 5:2-3 came rushing to my mind. "Indeed I, Paul, say to you that if you become circumcised, Christ will profit you nothing. And I testify again to every man who becomes circumcised that he is a debtor to keep the law." In one sense, people like my friend are why Paul wrote Galatians.
I. Paul's Astonishment (v. 6-7)
II. Danger, Danger, Danger (v. 8-10)