An angel of the Lord directed Philip to a lonely road that led from Jerusalem to Gaza, where an anonymous eunuch was floundering in his struggle to understand a prophesy of Isaiah.
The angel could have gone directly to the man seeking understanding, but as in all examples of conversion, the Lord operated through words spoken by men. There is no Bible example of a person being saved by a direct operation from God. The gospel was, and is, God’s power unto salvation (Rom. 1:16) and men must understand its message to be saved (Rom. 6:17,18; 10:17).
The prophecy of Isaiah fifty-three is clearly Messianic, but it is doubtful that even Isaiah understood what he wrote! Peter said the prophets who spoke of salvation in Christ sought to know, but did not understand things the Holy Spirit revealed through the apostles and other Spirit-guided men (1 Pet. 1:11,12).
Hindsight makes it easier to understand Isaiah’s description of the birth, ministry, death and resurrection of the Christ, but the eunuch had no idea whether Isaiah was talking about himself or someone else (v. 34). Philip used this open opportunity to “open his mouth” and preach Jesus to the man (v. 35). This is what he had done in Samaria, and with the same results (Acts 8:5,12,13).
The verses Philip heard the eunuch reading (Is. 53:7,8) are among the most difficult in the chapter and we still need help to understand! Homer Hailey’s commentary on Isaiah explains that from a violent miscarriage of justice (Pilate’s action, Jn. 19:4,16), Christ was delivered up to death, but His contemporaries did not understand that His death was for their own transgressions. The eunuch had a mind searching for truth. Philip opened his mouth and “preached Jesus,” which resulted in open obedience to the gospel (vv. 38,39).