constrain you to be circumcised
"Circumcision" stands here for externality in religion -- form rather than spirit. (Colossians 2:16-23).
Related Commentaries of Galatians 6:12
Galatians 6:12
12 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.