Galatians 6:13
For neither they themselves who are circumcised keep the law; but desire to have you circumcised, that they may glory in your flesh. For neither they themselves who are circumcised keep the law; but desire to have you circumcised, that they may glory in your flesh.
Galatians 6:13 stands in the closing portion of Galatians, which is as important now as to those first addressed. The whole letter including this verse was written by Paul with his own hand, contrary to his usual custom of having another write the body while he added the greeting and signature with his own hand. Weak eyes hindered him in writing so that he always needed someone with him to minister and to write for him, and false letters written in his name had troubled the brethren so that his own handwriting was the mark by which a letter from him could be known. His writing this whole letter himself shows consuming zeal and great urgency.
Those urging and compelling circumcision do not themselves keep the law, yet want the Galatians and Gentiles circumcised so they can boast and glory in their converts' flesh and outward mark and outward observance. Their aim was fleshly, worldly self-glory and a fair show in the flesh, not faithful obedience. They desired to make a fair show in the flesh and pressed circumcision on the Galatians only so they might not suffer persecution for the cross of Christ and for openly following the crucified Christ. Their work was a perversion of the gospel driven by the selfish principle of self-salvation that enters every false system of religion, seeking to glorify man and to draw seekers after themselves instead of after Christ, even when those deceived do not see the selfishness.
Fleshly circumcision is only an outward show of righteousness and works of the flesh. True circumcision is worshiping God in the Spirit, rejoicing in Christ, and having no confidence in the flesh, with the law written in the heart by God's Spirit. Those circumcised only in the flesh without keeping the law are counted as uncircumcised. This exposes their teaching as self-justification by works rather than the gospel, as part of an epistle correcting the teaching that salvation depends on human effort or works, whose central message is salvation through faith in Jesus Christ and justification by faith in Christ.
The verse exposes the insufficiency of ceremonial religion, for neither performing nor avoiding a ceremony brings salvation, because what is needed is a new creation. Boasting in the flesh denies the cross, which is the only proper ground for boasting. The verse shows that Christians are not to keep the law of Moses. In the distinction between that law and God's perpetual moral law, the verse belongs to the biblical evidence that the Levitical law was abolished by Christ, as evidence for the former and not the latter.