The word Samaritan
was a swear word for someone who was demon-possessed in Jesus’ time (compare John 8:48).
With the sending of the twelve apostles, Jesus gives the command to go to the lost sheep of Israel but to go nowhere near the Gentiles and enter no town of the Samaritans
(Matthew 10:5–6).
Jesus’ meeting with the Samaritan woman is special and tells us something about the Samaritans’ expectation of the Messiah. This meeting unfolds at Sychar, at Jacob’s old well (John 4:8–26). The Samaritan woman says to Jesus, among other things, that she knows that the Messiah is coming (John 4:25). Philip can possibly connect with the (vague) expectation of the Messiah. Perhaps he meets a group of Samaritans who knows Jesus as a result of Jesus’ visit in John 4 (many Samaritans believed in him,
John 4:39 and John 4:41). Jesus, with his visit to Samaria, has prepared the cross-over from Jerusalem to Samaria, as Philip now experiences it.
5 Philip went down to the city of Samaria and proclaimed to them the Christ.