Why wouldn't the Pharisees or Orthodox Jews go into Gentile congregations to teach them?
Pharisees and Orthodox Jews would not enter Gentile congregations because they viewed Gentiles as “dirty dogs” and would have nothing to do with them. The Jews who did come were Jewish believers who accepted Jesus as the Messiah of Israel but remained Law-keeping, not followers of Paul’s Gospel.
Les explains from Acts 15:1 that the issue involves Jews entering Gentile congregations. He notes that Orthodox Jews and Pharisees would never do such a thing because, in the mind of a Pharisee, Gentiles were dirty dogs. Therefore, the ones coming into these congregations must have been Jewish believers who confessed Jesus as the Christ. Yet they were not believers in Paul’s Gospel; they still believed Jesus was the Messiah of Israel and remained under the Law. Les points out that many do not realize these early Jewish believers under Peter’s preaching were still Law-keeping Jews.
And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved.
More Questions
Why weren't Orthodox Jews or Pharisees the ones teaching in the Gentile congregations?
The Orthodox and the Pharisees would not have gone into a Gentile congregation to teach, because in the mind of a Pharisee Gentiles were dirty dogs.
Who were the Jews that came into Gentile congregations teaching circumcision and the Law?
Those coming into the Gentile congregations were Jewish believers that Jesus was the Christ, not believers of Paul's Gospel, but still believing Jesus was the Messiah of Israel.