Adam Clarke on Galatians 6:12

A fair show in the flesh - The Jewish religion was general in the region of Galatia, and it was respectable, as it appears that the principal inhabitants were either Jews or proselytes. As it was then professed and practiced among the Jews, this religion had nothing very grievous to the old man; an unrenewed nature might go through all its observances with little pain or cross-bearing. On the other hand, Christianity could not be very popular; it was too strict. A Jew made a fair show there, according to his carnal system, and it was a temptation to a weak Christian to swerve into Judaism, that he might be exempted from persecution, and be creditable among his countrymen. This is what the apostle intimates: "They constrain you to be circumcised, lest they should suffer persecution for the cross of Christ."