Why did Peter minister to the Jews?
Peter ministered to the Jews to prove that the King was coming in fulfillment of the Abrahamic covenant. He served as the apostle to the Jew under the covenant program that began with Abraham, while Paul was later shown to be the apostle of the Gentiles.
Les explains that the early chapters of Acts are characterized by Peter ministering to the Jew, the Jew, the Jew. He notes he is anxious to get to chapter 9 and the conversion of Saul so the vast differences become more evident. Les teaches that Peter is the apostle to the Jew, while God clearly lays out Paul as the apostle of the Gentiles. These are two different groups of people and two different doctrines, yet the same God. Peter remains under the covenant program that began with Abraham, and he ministered to the Jew to prove that the King was coming in fulfillment of that Abrahamic covenant. Les also mentions that disagreement on these points does not make one a heretic, because the fundamentals remain the death, burial, and resurrection of Christ.