Who was bombarding the little churches Paul planted in Galatia?
The Judaizers—the Jewish element from Jerusalem—were bombarding the little Galatian churches Paul had planted. Whether Orthodox Jews rejecting Jesus or Judaizers who accepted Him as Messiah, both insisted that keeping the Law and practicing circumcision were necessary for salvation, contradicting Paul’s message.
Les explains that Paul wrote to the group of little churches he had no doubt planted himself, and they were now being bombarded by the Judaizers, the Jewish element from Jerusalem. He notes it could have been either the Orthodox who still rejected Jesus of Nazareth or Judaizers who had embraced Christ as Messiah; he doesn't think it makes much difference because both were hung up on keeping the Law and practicing circumcision for salvation. These Judaizers came into the little congregations Paul had planted through his sweat and blood and tears, telling them they could not be saved by Paul's message alone, that they could not be saved like he says.