Pamphylia was a Roman province that lay west of the kingdom of Antiochus, which was west of Cilicia, Paul's home province. Perga (modern Perge) stood 10 miles inland from the major seaport of Attalia (modern Antalya, cf. 14:25-26), but it had an inland harbor on the Cestrus River. In Perga, John Mark left Paul and Barnabas to return to Jerusalem. Paul did not approve of his decision (15:38), but Luke did not record Mark's motives. The commentators have deduced several reasons including homesickness (cf. 12:12), fear of illness (cf. Gal. 4:13), and fear of danger in the Taurus mountains north of Perga. Paul purposed to cross these mountains to get to Antioch of Pisidia. Others have cited the changes that were taking place in the mission's leadership from Barnabas to Paul. The most probable explanation, I believe, is disagreement over the validity of a direct approach to and full acceptance of Gentiles. John Mark, of course, had strong ties to the Jerusalem church and could well have resisted this approach as so many other Jews did.
