Q. In your John study guide, you have a note at the end of Session 8 that says the story of the woman who was caught in adultery “was most likely not an original part of the gospel of John.” Sure enough, in my Bible the passage is in italics and there’s a note that says, “The earliest and most reliable manuscripts and other ancient witnesses do not have John 7:53-8:11.” If that’s true, then who added stuff like this that wan’t there in the first place? And what are we supposed to do when we get to these parts? Ignore them?
The gospels were all written about a generation after Jesus lived. They’re based on a stream of oral tradition coming down from his day about what he said and did. Not everything in this tradition was put to use by the gospel writers. But in the case of the story of the woman who was caught in adultery, it seems that something more from this oral tradition found its way into the gospels after they were written.
This story appears at John 7:53-8:11 in some later manuscripts; it’s also found in different places in other manuscripts: after Luke 21:38, after Luke 24:53, after John 7:36, and after John 21:25. With so much attestation, it’s likely that this story is part of the genuine tradition coming down from Jesus.

None of the gospel writers included it, perhaps because it could be misunderstood to condone adultery. But it’s such a powerful episode when rightly understood (“let the one who is without sin cast the first stone”) that people who knew about it added it to the gospels later. This may originally have been as a “gloss” or marginal note, which later got added to the text itself. In several manuscripts it’s marked as an addition by asterisks or other symbols.
Bruce Metzger, who was of the leading textual critics of our day, writes in his Textual Commentary on the Greek New Testament that while “the case against … Johannine authorship appears to be conclusive” (that is, it’s pretty clear that John didn’t include this story in his gospel originally), the account “has all the earmarks of historical veracity. It is obviously a piece of oral tradition which circulated in certain parts of the Western church and which was subsequently incorporated into various manuscripts at various places.”
So even if we can make a good judgment that something probably wasn’t in the original manuscripts, we still need to ask whether it might be part of the tradition coming down from Jesus. In this case, the story probably is. That’s why I do encourage groups to discuss the story, just not as part of their regular meeting. In the study guide I say that the story “probably preserves a genuine episode from the life of Jesus” and I suggest that groups discuss it over dinner before doing the next session. (Even if a group didn’t usually have a meal together first, this would provide a good occasion to do that at least once.)