What does John 4:39 mean?
This is an interesting verse for several reasons. First , in that time and place, the testimony of a woman was considered unreliable. Women could only testify in court if three or four of them had co-witnessed the same event. And yet, it was the word of a woman which brought these Samaritans to meet Jesus (John 4:28–30). Strictly speaking, this verse is not saying that the people of town were saved on account of the woman's story. Rather, it was her story which led them to meet Jesus, resulting in their belief and salvation.The other interesting point is that Jesus' extensive knowledge is specifically mentioned. In that place and time, a woman's opinion might have been pointless under normal circumstances. However, this woman might well have had less-than-honorable connections to other men in town (John 4:17–18). When she said that Jesus knew "all" she had done, that might have made some people nervous enough to go investigate.
This is also a prime example of why evangelism efforts are never wasted. There is no such thing as a person too far gone, too sinful, or too unimportant to share the gospel with. A lowly, outcast Samaritan woman was so impressed by Jesus that she sparked a revival in her town! The impact of her actions are still being felt in the Christian world today.