In their departure from the truth, the Galatians have not considered the effect this will have on the apostle. Like children who take their parents for granted and create all manner of problems by their bad behaviour, so the Galatians have caused much worry and heartache for Paul, and necessitated urgent steps for their recovery.
It is right that a pastor should speak like this at times, for it is the fault of the people when they fall into gross errors like this, since God had given them all that was necessary to remain faithful to his word and avoid such an error. They should not have needed to be corrected so forcefully, nevertheless the Lord does not give up with his true people even when they are rebellious and the Scriptures are profitable for correction also.