Those who want to impress people by means of the flesh are trying to compel you to be circumcised. The only reason they do this is to avoid being persecuted for the cross of Christ. Not even those who are circumcised keep the law, yet they want you to be circumcised that they may boast about your circumcision in the flesh.
Now we get to the nub of the motive of the Judaizers. They have no concern for the Galatian Christians - they simply want to keep in well with the unconverted Jews. They are hypocrites. They see the Galatians as a series of scalps to be taken.
We should be wary of our evangelism that we don't have the same attitude. Winning souls for Christ is not a numbers game, but implies a love of people who are lost and a lifetime commitment to them.