Why did the Holy Spirit direct Philip to the chariot of the Ethiopian official?
God is sovereign and had an intrinsic interest in this situation, so the Holy Spirit directed Philip to that particular person. God uses common, ordinary human instruments—not angels or elite scholars—to lead people to salvation. The official was reading Isaiah 53, so Philip could explain the finished work of Christ.
Les teaches that God is sovereign and in control of every detail He wants to control. God had an intrinsic interest in this situation, so the Holy Spirit directed Philip to this particular person. Philip ran to him, heard him reading Isaiah, and asked if he understood. The official replied, "How can I?" Les explains that God did not leave His Word in the hands of angels or highly educated seminarians; He placed it, with the Holy Spirit's leading, into the hands of every person willing to handle it. For those who will be made aware of the plan of salvation, God does not send an angel or a super-educated person, but uses common, ordinary people. Les notes it is rare for someone to come to salvation by simply reading the Bible alone; normally it takes a human instrument, and here Philip is that instrument. The official was reading Isaiah 53, still an appropriate portion for approaching Jews about the finished work of Christ and His First Advent.