That this man was in Jerusalem and is reading a scroll of Isaiah indicates that he is a Jew, despite the fact that he is living in Ethiopia. Some (older) commentaries argue that the Ethiopian was a Gentile. Since there is no church that develops from his conversion, there is not a problem integrating him into Israel as a convert to “Jewish Christianity.” Most important, the conversion of Saul in the next chapter heralds the beginning of Gentile mission.
But as Darrell Bock points out, Luke makes Cornelius significant as the first Gentile convert, albeit as a God-Fearer (Acts, 338). As with the Samaritans, we are geographically moving outward from Jerusalem, but also culturally. If the Samaritans are the fringe of Judaism, so too would be a Gentile convert from Ethiopia, a land that was considered to be the very “ends of the earth” (Witherington, Acts, 290, citing Herodotus, Hist 3.25.114, Strabo, Geog. 1.1.6).
The fact he is reading from Isaiah is an indication that the man is at least a Jewish convert. A scroll of Isaiah would have been a costly book and quite large. Either this is a purchase for his synagogue, or he is reading and extract from a larger scroll. In addition, he is reading aloud, often associated with memorization of the text (m.Aboth 6.5). The scroll could be in Hebrew or Greek, the text as cited in Acts follows the LXX, but the sense is the same in the Hebrew. If he were reading a section of Isaiah in Hebrew, then this is confirmation that the Ethiopian was a Jew (although the language of the scroll does not matter).
He is described as a Eunuch and in charge of the treasury of Candace, queen of Ethiopia. Ethiopia is not the same as the modern country, but biblical “Cush,” south of Egypt, in the central Sudan. It is a five month journey from Jerusalem to Cush through inhospitable desert. Presumably he was either in Jerusalem from Passover, stayed through Pentecost and is only now returning home to Ethiopia. He is traveling south to the coast. Gaza is the last place to stop for water before the road turns south for the Egyptian desert (Bock, Acts, 341).
The Eunuch is reading from Isaiah 53, the great servant song. The identity of the servant was an open question in the first century, but few would have identified the servant as the Messiah. Philip uses the ambiguity of the text as an opportunity to explain that Jesus of Nazareth is the suffering servant.
When Philip approaches the Ethiopian, he asks if he understands the text. The Ethiopian states humbly that he cannot understand unless he has a guide – the purpose Philip has been brought to the place. The question the man concerns the subject of Isaiah 53. Jews in the Second Temple period would have that the passage described either Isaiah or some other person (like a new Elijah); if the messiah was in view, it was not a suffering messiah at all.
Philip “begins with that very passage” to explain the gospel with the Ethiopian. Philip identifies Jesus as the innocent sufferer of Isaiah 53, making it clear that the new age described in Isaiah 56 has begun – that even Eunuchs may enter into complete fellowship with God in worship.
If the Eunuch is in fact from an Ethiopian family of Jewish proselytes, then Philip is extending the Gospel into new a social and cultural context, but he is not yet reaching out to the Gentiles. But he is doing ministry like Jesus did, finding Jews who were on the margins of what it meant to be Jewish from the perspective of the Temple aristocracy, the Pharisees and others at the center of Jewish faith in Jerusalem.