Circumcision represents a desire to be under law, a desire to contribute your own works to your salvation. If you seek to be made right with God through your own law keeping, then you have no need for Christ and his law keeping in your place. Then Christ is of no value to you and you practically demonstrate that you do not believe his life and death was sufficient for your salvation.1 Circumcision (personal law keeping) and faith in Christ are thus presented as two different and contrasting means of receiving profit (God’s favour).2
2 Look: I, Paul, say to you that if you accept circumcision, Christ will be of no advantage to you.