From that city many of the Samaritans believed in Him because of the word of the woman who testified, “He told me all the things that I have done.” So when the Samaritans came to Jesus, they were asking Him to stay with them; and He stayed there two days. Many more believed because of His word; and they were saying to the woman, “It is no longer because of what you said that we believe, for we have heard for ourselves and know that this One is indeed the Savior of the world.”
4-Point Calvinist, Ron Rhodes, comments: “It is certain that when the Samaritans called Jesus ‘the Savior of the world,’ they were not thinking of the world of the elect.” (The Case for an Unlimited Atonement, emphasis mine)
John Calvin comments: “Christ proclaimed that the salvation he brought was for the whole world, so that they would more clearly understand that it also belonged to them. For Christ did not say that they were heirs according to law, as was the case with the Jews, but he taught them that he had come to admit strangers into God’s family and to bring peace to those ‘who were far away’ (Ephesians 2:17).” (John: Calvin, The Crossway Classic Commentaries, p.112, emphasis mine)
Salvation was brought to the whole world because God “so loved the world.” (John 3:16) And if God so loved the world, the Calvinistic doctrine of Unconditional Reprobation implodes.
While salvation is indeed to the Jew first, and then the Gentile (Romans 1:16), that’s from the perspective that both camps are lost sheep, and in need of salvation, despite Israel’s election. In contrast, with an alleged, eternal flock of the Father type Election, none in that flock could ever, genuinely, be considered lost.
Here is a Blog discussion on John 4:42.