F. F. Bruce (1910–1990) and J. C. Ryle (1816–1900) on John 4:42

NKJ John 4:42 Then they said to the woman, "Now we believe, not because of what you said, for we ourselves have heard Him and we know that this is indeed the Christ, the Savior of the world."

Bruce wrote:

He was not only the prophet like Moses, but also the Saviour of the world. This title appears twice in the Johannine writing (the other instance being in 1 John 4:14); it is in line with the statement of John 3:17, that God sent his Son into the world 'in order that the world might be saved through him'. The use of the title in this context suggests that the Samaritan mission represents the first outreaching of Jesus' grace beyond the confines of Judaism.

F. F. Bruce, The Gospel of John (Grand Rapids: Eerdmans, 1989), 116.

Ryle comments:

Whether the Samaritans clearly understood what they meant when they spoke of our Lord as "the Saviour," may be reasonably doubted. But that they saw with peculiar clearness a truth which the Jews were specially backward in seeing that He had come to be a Redeemer for all mankind and not for the "Jews" only, seems evident from the expression "the world." That such a testimony should have been borne to Christ, by a mixed race, of semi-heathen origin, like the Samaritans, and not by the Jews, is a remarkable instance of the grace of God.

J. C. Ryle, Ryle's Expository Thoughts on the Gospels (Grand Rapids: Baker, 1979), 3:250.

Elsewhere I stated the following:

The idea of this passage is not to focus on what God has secretly determined to do through the appointed Savior, but that Christ should be the appointed Savior to whom all of apostate humanity (the "world"), Jew and Gentile alike, should look for salvation. So, the sense of "world" does not connote the elect, or even an abstract class of thing without involving all the particulars of that class. It references all of apostate humanity on the earth at any given point, and Christ is to be their appointed means of salvation. "Savior of the world" speaks to his office (or title) as mediator, as well as to what he wills to do for humanity. It further spells out what is means for him to be "Christ."