Galatians 6:11 Ye see how large a letter I have written unto you with mine own hand.
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.
13 For neither they themselves who are circumcised keep the law; but desire to have you circumcised, that they may glory in your flesh.
Here we see Paul wrote this letter himself to make sure the Galatians knew he, not some forger, was writing it, and to personalize the document, given the importance and severity of its contents. The Judaizers were motivated by religious pride and wanted to impress others with their external piety. They were more concerned about their personal safety than correct doctrine by adhering more to the Mosaic law than to the gospel of Jesus.It appears that even though they have proclaimed Jesus as their Savior, they are not willing to suffer the ridicule from their Jewish brothers. They were not willing to suffer for Christ. They are trying to prove how religious they are by telling that they are circumcised. They do not even keep the law themselves, but want to impose this custom on others to show their religion. They were trying to stay in both camps. Again Paul is reminding the Galatians that circumcision is not necessary because the law was fulfilled through Jesus Christ.