Why were the first Christians called Christians in Antioch rather than in Jerusalem?
The designation first arose in Antioch because the believers being saved there were Gentiles, saved under the Pauline message of God’s grace. Jerusalem’s earlier believers were not identified by that name in the passage; the context ties the new name to the Gentile church gathered at Antioch.
Les explains that they were called Christians first in Antioch because these were Gentiles who were being saved by the Pauline message of God's grace (s585-s587). The context then shows prophets coming from Jerusalem to Antioch, including Agabus, who predicted a great dearth in the days of Claudius Caesar (s588-s594). The Gentile believers there determined to send relief to the brethren in Judea by Barnabas and Saul (s595-s599). Les contrasts this with Acts chapter 2, where believers sold everything and placed it in a common kitty, which eventually ran out (s600-s610).