John 4.39-41: Many Samaritans from that town believed in him because of the woman’s testimony, “He told me all that I ever did.” (40) So when the Samaritans came to him, they asked him to stay with them, and he stayed there two days. (41) And many more believed because of his word. (ESV)
In the verses prior to verse 39, the woman of Samaria gave persuasive testimony of what Jesus had revealed to her about her life history. Information that Jesus only could have known by divine revelation. There is no express statement here that she believed in Jesus as the Messiah. In fact, when she asks in verse 29, “Can this be the Christ?”, she gives a very definite signal in the way she asks the question that the expected answer is “no”. She may have given this signal for a rhetorical purpose, or to indicate that she tentatively thinks Jesus may be the Messiah*, but in any case I think it is reasonable to conclude that she was eventually convinced of his Messiahship and believed in him, because of the way the people of the town did in fact believe in Jesus as Savior, in response to her testimony. *see Dods’ commentary in The Expositor’s Greek Testament
Verse 39 says that many of the people of Samaria “believed” in Jesus because of the woman of Samaria’s testimony to them, and in verse 41 it says that many more believed in him because of his word to them, after Jesus had stayed with them two days. The operative word “believed” used in describing the citizens of Samaria accepting Jesus as Savior has built within its meaning the ideas of “trusting”, “relying upon”, and “accepting”. The Theological Dictionary of the New Testament edited by Kittel and Friedrich is a great resource for a fuller understanding of this word’s use in the New Testament.