The first major controversy the early church had to contend with strikes the modern reader a bit strange. Rather than debating who Jesus was or beginning to develop the doctrine of the Trinity, the first major theological problem to solve was the status of the Gentile who has put their faith in Jesus. Are Gentiles converting to Judaism? If so, then at what level ought they keep the Law? Are they “God Fearers”? Perhaps there is an implied secondary status for the Gentile who believes in Jesus as savior but does not fully convert to Judaism and keep the Law.
Why was circumcision of Gentiles such a controversial issue? In Acts 13-14 Paul begins to have success among Gentiles and establishes several churches that have mixed congregations of Jews and Gentiles. That these churches included some Gentiles who were not previously “God Fearers” seems to be clear from the response Paul gets in Lystra.
Sometime after Acts 14, some teachers arrived in Paul’s Gentile churches and told the Gentiles that they were required to fully convert to Judaism in order to be fully a part of the people of God in the present age. I think that this teaching focused on the boundary markers of food and Sabbath as well, but Galatians and Acts 15 is concern only the practice of circumcision. If Gentiles are going to be considered full participants in the people of God in the present age, they must be Jews; this requires conversion and obedience with the law.
This is no small controversy for several reasons. First, circumcision was a major factor in Jewish identity. For many in the Greco-Roman world, it was circumcision which set the Jews apart, usually for ridicule. Marital, for example, seems to find a great deal of humor in the Jewish practice (Epigrams 7.35.3-4; 7,82, 11.94. Some of Marital’s comments on circumcision are so crude the original Loeb translators did not translate them into English so as not to offend sensitive readers, choosing instead to translate them into Italian. A new edition of Marital has been produced for the Loeb series by D. R. Shackleton Baily which not only translates these epigrams, but seems to strive to offend!)
Second, Paul argues in Galatians and other letters that the church is neither Jew nor Gentile (Gal 3:28). If Gentiles convert to Judaism, then the church is Jewish; if a Jew rejects the Law and acts like a Gentile, then the church is “Gentile.” Paul’s point is that there is something different than Judaism happening in the present age, the “church” is not a form of Judaism, nor is it a Gentile mystery religion. The church in Paul’s view transcends ethnicity (neither Jew or Gentile), gender (neither male or female) and social boundaries (neither slave nor free).
For Paul, if the Gentiles are forced to keep the Jewish boundary markers, then they have converted to Judaism and they are not “in Christ.” This view would have been radical in the first century, and it still is difficult for Christians two thousand years later. One does not “act like a Christian” to be right with God, any more than one “acted like a Jew” in the first century to be right with God.