Acts 8: 25-40:
So, when they had solemnly testified and spoken the word of the Lord, they started back to Jerusalem, and were preaching the gospel to many villages of the Samaritans.
But an angel of the Lord spoke to Philip saying, “Get up and go south to the road that descends from Jerusalem to Gaza.” (This is a desert road.) So he got up and went; and there was an Ethiopian eunuch, a court official of Candace, queen of the Ethiopians, who was in charge of all her treasure; and he had come to Jerusalem to worship, and he was returning and sitting in his chariot, and was reading the prophet Isaiah. Then the Spirit said to Philip, “Go up and join this chariot.” Philip ran up and heard him reading Isaiah the prophet, and said, “Do you understand what you are reading?” And he said, “Well, how could I, unless someone guides me?” And he invited Philip to come up and sit with him. Now the passage of Scripture which he was reading was this:
“He was led as a sheep to slaughter;
And as a lamb before its shearer is silent,
So He does not open His mouth.
“In humiliation His judgment was taken away;
Who will relate His generation?
For His life is removed from the earth.”
The eunuch answered Philip and said, “Please tell me, of whom does the prophet say this? Of himself or of someone else?” Then Philip opened his mouth, and beginning from this Scripture he preached Jesus to him. As they went along the road they came to some water; and the eunuch *said, “Look! Water! What prevents me from being baptized?” [And Philip said, “If you believe with all your heart, you may.” And he answered and said, “I believe that Jesus Christ is the Son of God.”] And he ordered the chariot to stop; and they both went down into the water, Philip as well as the eunuch, and he baptized him. When they came up out of the water, the Spirit of the Lord snatched Philip away; and the eunuch no longer saw him, but went on his way rejoicing. But Philip found himself at Azotus, and as he passed through he kept preaching the gospel to all the cities until he came to Caesarea.
After John and Peter return to Jerusalem we do not see much controversy about the Samaritans coming to Christ. Most like this is because of two factors 1) They are half Jewish and 2) Jesus has done a lot of ground work in Samaria before himself and has already dealt with this prejudice personally with his disciples.
Philip finds himself lead into the wilderness because of the leading of an angel. It sets up an encounter with a court official of the Queen of Ethiopia who is also a eunuch. The eunuch is obviously quite wealthy and he also has a knowledge of the Scriptures and owns copies of them. His problem is that he does not understand them and Philip is guided into explaining to him the meaning of Isaiah’s passage.
Philip uses the opportunity to tell the eunuch about Jesus as the fulfilment of what he is reading. When the eunuch is finally convinced he asks to be baptized and once it is done Philip literally disappears. Finding himself at Azotus he does a tour that runs from there to Caesarea before he finally settles down. All along the way the message of the gospel spreads.
It should be noted that tradition says that the eunuch was instrumental in bringing Christianity to Ethiopia which has for the most part remained Christian to this day.
Next: The Conversion of Saul