The judaizers from Jerusalem not only attacked what Paul taught; they also attacked him personally, impugning his integrity and calling his apostleship into question.
I think it’s pertinent that we never hear the names of these rascals, but Paul is known around the world and through the centuries.
If they were to be successful in shaking the new believers in Galatia in their faith, then they had to shake their faith in Paul. Why, you may wonder, would anyone want to do either of those things? What did the judaizers have to gain? Was it a matter of authority and control? Were the judaizers simply untaught themselves? Did they truly believe that the Law still needed to be observed in order for people to obtain salvation?
Probably a little of all the above. I’m inclined toward their dislike of giving up authority, myself. It will be interesting to see what we learn as we walk through the book.
When Paul heard what was going on in Galatia, he wasted no time in penning a strong reproof, gentled with great love, to his converts. In fact, he was in such a hurry to write to them that he didn’t wait for an amanuensis (secretary) as was his usual practice, but he wrote the letter with his own hand. Toward the end of the book, he refers to how large a letter it is. Paul very likely had some kind of vision problem, and wrote in large letters, taking up lots of manuscript. That he did it in his own writing was a proof of his strong desire to help the Galatians get back on track.