I am preparing to preach my last sermon on the gospel of Mark and, inevitably, the issue of the longer ending of Mark is something that must be addressed. Rather than writing out my thoughts, I have found James Edward’s handling of the issue in his commentary to be a wonderful primer on why we should regard Mark 16:9-20 as an inauthentic, later addition to Mark’s gospel:
It is virtually certain that 16:9-20 is a later addition and not the original ending of the Gospel of Mark. The evidence for this judgment is complex, and the problems are necessary to discuss in some detail before discussing the secondary ending itself. Since none of the autograph copies of documents of the NT survive, the Gk. text of the NT is constructed from later copies of manuscripts dating from A.D. 135 at the earliest to about A.D. 1200 at the latest. These copies, of which more than five thousand exist, range in size from scraps little larger than postage stamps to complete manuscripts of the Bible. In general, these copies show remarkable agreement among themselves. The most notorious exception to this otherwise happy rule, however, is the ending of Mark, which presents the gravest textual problem in the NT. The two oldest and most important manuscripts of the Bible, codex Vaticanus (B) and codex Sinaiticus (א), omit 16:9-20, as do several early translations or versions, including the Old Latin, the Sinaitic Syriac manuscript, about one hundred Armenian manuscripts, and the two oldest Georgian manuscripts. Neither Clement of Alexandria nor Origen shows any awareness of the existence of the longer ending, and Eusebius and Jerome attest that vv. 9-20 were absent from the majority of Gk. copies of Mark known to them. An ingenious system of cross-referencing parallel passages in the Gospels that was devised by Ammonius in the second century and adopted by Eusebius in the fourth century (hence the name Eusebian Canons) does not include Mark 16:9-20. The apocryphal Gospel of Peter is absent the longer ending, and concludes, as does Mark 16:8, with the fear of the women. Although a majority of ancient witnesses, including Gk. uncial and minuscule manuscripts, church fathers, and versions in other languages do include vv. 9-20, this does not compensate for the textual evidence against them. The inclusion of vv. 9-20 in many manuscripts is accounted for rather by the fact that the longer ending, which must have been added quite early, was naturally included in subsequent copies of the Gospel. Many of the ancient manuscripts that do contain the longer ending, however, indicate by scribal notes or various markings that the ending is regarded as a spurious addition to the Gospel. External evidence (manuscript witnesses) thus argues strongly against the originality of the longer ending. The secondary nature of the longer ending is further corroborated by the application of the techniques of literary criticism to 16:9-20. This is apparent beginning in the first verse of the longer ending, which is a conspicuous non-sequitur: whereas the subject of v. 8 is the frightened and fleeing women, v. 9 begins presupposing the resurrected of Jesus, who appears to Mary Magdalene. The latter, moreover, is introduced as a newcomer ("out of whom [Jesus] had driven seven demons," v. 9), although Mark has mentioned her three times immediately before (15:40, 47; 16:1). In vv. 9-20 Jesus is for the first time in Mark referred to as the "Lord Jesus" (v. 19), or simply "the Lord" (v. 20), rather than Mark's custom of calling Jesus by his given name. Such reverential nomenclature likely derives from later Christian worship. Particularly noticeable is the number of new words that appear nowhere else in Mark. In the so-called shorter ending of Mark nine of the thirty-four words are new, and in the longer ending there are an additional eighteen words that otherwise do not appear in Mark, plus several unique word forms and syntactical constructions. Several of Mark's signature stylistic features are likewise absent from the longer ending. The longer ending also includes themes peculiar to itself, some of which contradict Markan themes. The repeated chastisement of the disciples for their "disbelief" (Gk., apistein; apistia; vv. 11, 14, 16) of the gospel proclamation (Gk., kerygma; vv. 11, 13, 14, 15, 16-18, 20) is unique to the longer ending, and the prominence given to charismatic signs in vv. 17-18 stands in stark contrast to the reserve of Jesus in Mark with regard to signs and sensation (cf. 8:11-13).
As to why someone would fabricate an ending to be attached to the closing of Mark, he explains:
The concern of the longer ending is with content rather than style, i.e., to rectify the omission of a resurrection appearance of Jesus in Mark. This has been accomplished by adding a resurrection harmony composed of texts from the other three Gospels. Since Mark's lack of a resurrection appearance is unique among the Gospels (and this includes the apocryphal gospels and those from Nag Hammadi), and since we do not possess an extant text similar to the longer ending, it may be that vv. 9-20 were composed especially with the problem of Mark's ending in mind.
So, what about Mark’s weird ending? Why end it with such an abrupt closing?
The chief remaining question concerns the original conclusion of the Gospel of Mark. There are two possibilities. One is that Mark concluded at 16:8. This is the position held by a majority of recent interpreters of Mark. In this view, Mark intentionally leaves the conclusion "open-ended." For some scholars Mark has given enough clues in the body of the Gospel for readers to supply the resurrection account themselves. For others the inconclusive ending halts readers in their presumption to preempt the conclusion of the story, forcing them to unconventional responses. For others the sober ending demands readers to ponder the cross and discipleship rather than taking refuge in enthusiasm and triumphalism. Still others suggest that since Jesus' "original Jewish disciples didn't get the message," that the risen Jesus is to be found in a Gentile gospel for Gentile readers. In these and similar interpretations, the final word of "fear" in v. 8 leaves readers, like the women, in a state requiring a response of faith. A resurrection announcement as opposed to a resurrection appearance is sufficient, in this view, because for Mark faith is elicited by hearing rather than by sight. The conclusion to the Gospel of Mark must be supplied, in other words, by each reader's response of faith. The chief argument in favor of this view is that our earliest and most reliable manuscripts end the Gospel at 16:8. This is a strong argument and it is held by excellent scholars. In my judgment, however, the argument is not persuasive. The suggestion that Mark left the Gospel "open ended" owes more to modern literary theory, and particularly to reader response theory, than to the nature of ancient texts, which with very few exceptions show a dogged proclivity to state conclusions, not suggest them.
So what does Edwards think happened? He thinks that the real ending of Mark’s gospel was lost. After listing several lengthy arguments for why he is skeptical that the gospel intentionally ended at verse 8, he then explains:
What might have happened to the original ending we shall probably never know. The most plausible suggestion is that it was lost due to wear-and-tear on the last leaf of a codex. Or perhaps Mark was interrupted or died before completing it. The latter suggestion is a distinct possibility if Mark composed his Gospel, as we suspect, in the mid-sixties of the first century. It would not be surprising if Mark's name were among the martyrs of Nero's reign.
As for myself, while I am certain the longer ending (16:9-20) is spurious, I am personally unsure about whether or not Mark intended to end the gospel the way we currently have it now, or the original ending was lost. In the Lord’s providence, however, He has determined that–whether intentionally or accidentally done–all we need now is up to 16:8.