Apart from Peter there is one dominant figure in the Acts, namely the apostle Paul. Stephen gives his testimony, and seals it with his blood; and Saul of Tarsus is thereby sealed unto the Lord, to carry forward the Gentileward movement so clearly perceived and enunciated by Stephen the Hellenist. Barnabas, Philip, and Mark, all prepare the way for Paul, and then disappear. Even Peter, when his work is done, "goes to another place" (xii. 17), and drops out after introducing Paul in the fifteenth chapter. Matthias is appointed but never again mentioned by name. James appears in connection with Paul, and disappears. John soon passes off the scene. We do not know where John went, or what he did. We have no record of the doings of Barnabas after xv. 39.
Saul of Tarsus enters the arena in Acts viii., and soon becomes the central figure of the book. For twenty chapters out of twenty-eight every incident recorded has some direct relation to the equality and independence, the peculiar ministry and faithfulness, of the apostle to the Gentiles. May the obvious intention not be lost upon us, who by nature were:-
"Gentiles in the flesh . . . . without hope, without Christ, without God, in the world" (Eph. ii. 11,12).
from page 30, Apostle of the Reconciliation