Several commentators doubt the reality of this story. They find it unlikely that an angel speaks up and Philip suddenly appears and later disappears again without a trace, and that this foreigner happens to read from Isaiah 53:1–12 and so quickly comes to faith and is then baptized! Some think that Luke (or a later editor) uses a tradition to give the party
of Greek-speaking Christians (with Philip) the right of way over the party
of Jewish Christians (with Peter). That would then explain why the conversion of the Ethiopian eunuch precedes the repentance of the first Roman officer Cornelius. Philip would then have the scoop of mission among the Gentiles. Regardless of this unproven battle between interests of parties,
the historical validity of this is wrongly being questioned. For after all, Luke writes an orderly account for Theophilus (Luke 1:1–4; Acts 1:1–3) and knows the facts firsthand from the witnesses he heard, for he stays together with Paul at Philip’s home in Caesarea (Acts 21:8–9). Therefore, Philip is the first and best witness for Luke, who gets to hear exactly what and how things have happened during this special encounter between Philip and the man from Ethiopia!
26 Now an angel of the Lord said to Philip, “Rise and go toward the south to the road that goes down from Jerusalem to Gaza.” This is a desert place.