The theme of this section of Scripture is cutting: cut in on, circumcision, and emasculation. Paul, in a very strident manner, rebukes the false teachers who teach law-works. False teaching always harms the flock and must be refuted. We need to reject a crossless Christianity. Here we emphasize the universal call of the gospel. The Lord's flock consists of those who respond to it in faith. The Lord's flock is precious to Him and must be guarded by church leadership.

Video courtesy of Gospel of Grace Fellowship.
Handouts available here:
https://www.ggf.church/sermons/sermon/2014-02-09/cut-in-on-by-false-teachers-galatians-5:7-12