One of the most famous moral teachings of the New Testament is “Judge not lest ye be judged.” It’s a favorite with pastors and politicians alike, and no individual story so exemplifies this maxim as Jesus’ encounter with the woman caught in adultery in the Gospel of John. A woman "caught in the act" is brought to Jesus by the scribes and Pharisees. They ask him if she should be stoned to death in accordance with the law given by Moses. At first Jesus ignores them and writes on the ground. When the accusers continue to challenge Jesus, he does not take the bait. Instead he asks that the person who is “without sin” cast the first stone. Nobody condemns the woman and Jesus tells the woman that he does not condemn her either and that she should go and sin no more.

The problem is that this story wasn’t originally in the Gospel of John. It didn’t become part of the Bible until at least a hundred years after the Gospel of John was written.

The earliest manuscripts of the Gospel of John show no trace of the story. It’s simply not included in the text. The two earliest manuscripts of John (known as P66 and P75), which were written in the second and early third centuries, do not include it. Nor do the mid-fourth century books Codex Sinaiaticus and Codex Vaticanus, the earliest complete collections of the New Testament. So where did the story come from and how did it make it into our Bibles?

In the new book To Cast the First Stone: The Transmission of a Gospel Story (Princeton, 2018), scholars Jennifer Knust and Tommy Wasserman explore the tangled and complicated history of this beloved story. In it they argue, as others do, that the story was introduced into the Gospel of John by a later interpolator sometime in the third century. Some other ancient authors refer to the story as part of different literary tradition, a lost ‘gospel’ known as the Gospel of the Hebrews. That interpolator presumably believed that the story was important and authentic and added it into the text of the Gospel of John. Looking at the manuscripts themselves it’s possible to watch that happen. One manuscript, Codex Sangallensis 48, leaves a blank space in John 7:53-8:11, the place where the story is usually found.

Though they are careful to point out that we don’t know for sure where the story came from or why it was added to the Gospel of John, Knust, an associate professor of New Testament and Christian Origins at Boston University, and Wasserman, a professor of Biblical Studies at Ansgar Teologiske Høgskole in Norway, told The Daily Beast that the interpolation took place “in a context where Greek was used but Latin was also spoken, and probably because the interpolator thought it fit best into that Gospel.” They added that “we can only speculate about why John and not some other Gospel,” but mentioned several theories, including the prominence of stories about women in the Fourth Gospel. They also note the intriguing theory of New Testament scholar Chris Keith that, in addition to portraying Jesus as forgiving, the story also presents Jesus as able to write. Perhaps it was added, then, to combat the scandalous accusation that Jesus wasn’t fully literate.

“Once it was added,” they said “it made sense to many Christians to read it there.”

The story proved enormously popular. In part, Knust and Wasserman told me, because “[it] fits well within a number of stories and sayings that also highlight the forgiveness or rescue of women who either engage in sexual misconduct or are falsely accused of doing so.” But also because it is intrinsically interesting to people and can be read in a variety of ways.

“One of the attractive aspects of this story is that it can be interpreted in multiple and diverse ways. In the earliest period of its telling, for example, some Christians seem to have thought that the woman was innocent and that Jesus, like the prophet Daniel, intervened to save her from a false accusation. Stories that leave a lot to the imagination often have significant staying power.”

Once the version of the story we have in John was placed into the Gospel, “it began to spread and a majority of Greek and Latin copies available in Rome, Italy, and Spain included it there.”

One of the most interesting findings of the book is how the authors trace the history of the manuscript in artistic and liturgical contexts, not only literary ones. What they discover is that the story not only had a great deal of staying power, it also captured the imagination of important fourth-century bishops, like St. Augustine, who referred to it in their sermons as well as their theological treatises.

Much of the life of the story is about its use in day-to-day life. It was also incorporated into the regular Roman liturgy, and with that move it began to be read aloud to ordinary Christians who lived in Rome. It was popular, Knust and Wasserman found, in the Latin-speaking Western part of the Roman empire. “Carolingian rulers employed the story to support a Christ-centered royal theology that, they argued, supported their role as rulers. The story was less well-known in the Greek East, but even there we find traces of groups telling the story…Byzantine Christians heard the story read in the context of various saints days.”

Knust and Wasserman are not the first modern scholars to notice that the story about the woman caught in adultery is missing from the earliest manuscripts of the gospels. But modern scholars aren’t the first to comment on this either, they are just the first to be scandalized. From the fourth century onwards, Knust and Wasserman show, Christian writers remarked upon the fact that the story couldn’t be found in all of the manuscripts and were considerably less concerned about this than we are.

One of the most fascinating arguments of the book is that while Christians knew there were problems with the text, it wasn’t the “faith killer” that it is today. Knust and Wasserman show that interest in the “original version” and “accuracy” of the New Testament texts is very much a recent phenomenon that began in the 18th and 19th centuries with the rise of critical scholarship.

Prior to that, and in the early Church in particular, Christians were more likely to have been used to thinking about the Jesus story in practice, rather than on paper. As they told me, “The stories and sayings Christians tell, hear, read, copy, illustrate, and perform, in and out of church, have always been as important—even more important!—for determining beliefs about ‘the gospel’ than the words in a given text.”

What the history of this story shows, as Knust and Wasserman so deftly demonstrate, is that even though this story doesn’t belong to the author of the Gospel of John (and, many might argue, probably never happened), this isn’t the central point. To early Christians this story had “broad appeal,” and that appeal was not exclusively grounded in the claim that it was historically accurate. As they write in the conclusion to their book, the “lesson” of the woman caught in adultery isn’t just that the text of the Gospels changed, but that what survived and counted as ‘authentic’ was greatly influenced by local liturgical traditions.