The Samaritan believers did not become the foundation of the church. They were quick to believe, and their belief was genuine. In just two days, Jesus had enough believers in a single Samaritan town, that from a human perspective, they could have been the first church. Instead, Jesus left them to return to Galilee.
He did not reject them as the foundation of the church because he was bigoted or racist; He went to them first to demonstrate just the opposite. He knew that his church would eventually reach the Samaritans and the Gentiles. He planned for the church to reach to the far corners of the earth.
Jesus did not leave because His ministry among the Jews would be easier; He knew it would not. The Samaritans believed quickly, without requiring miracles, but Jesus knew it would be hard to convince the Jews. They would require miracles, and even then, many would be too hardhearted to believe. The Samaritans embraced him, but the Jews were going to kill him.
Jesus did not go on to the Jews because he loved the Jews more than the Gentiles; God loves all humanity and does not show favoritism.
Jesus went to the Jews because God had chosen the Jews. He chose them for a purpose, not for a position. He blessed them to make them a blessing to the whole world. They were holding tight to “We are chosen,” while neglecting “for a purpose.” Jesus went to Galilee to make sure God’s purpose was fulfilled.
Because the Samaritans rejected most of the Old Testament, they did not have the theological foundation required to fulfill the mission that Christ was going to give the church. The Old Testament teaches truth about God, humanity and righteous relationships. When we believe in Christ, we are blessed and made righteous. We must never forget that we are blessed to be a blessing, and to bless the world we need the theological truths of the Old Testament. Belief in Christ does not destroy the law, but writes the law upon our hearts.