Paul is referring to the Jewish Christians, likely outsiders who came from Judea (Acts 15:1–2; Galatians 4:17). 1 Apparently, if they could get the Gentile Christians in Galatia to be circumcised, it would reflect well on them so that they would get praise from fellow Jewish Christians and/or the Jewish community as a whole. 2
12 It is those who want to make a good showing in the flesh who would force you to be circumcised, and only in order that they may not be persecuted for the cross of Christ.