Nearly all modern Bible scholars have concluded that all of what appears at Mark 16:9-20 were not written by Mark but were added by a later hand. This conclusion is based on both external and internal evidence.
First of all, there is the telling fact that two of the oldest and most highly regarded Bible manuscripts, the Vatican 1209 and the Sinaitic, do not contain this section; they conclude Mark’s Gospel with verse eight. There are also a number of ancient manuscripts that contain a short ending of just about one verse beyond eight; and other manuscripts contain both conclusions. So, some manuscripts end with verse eight, others have a short ending, others have a long ending, and some even give both endings. In addition to this testimony of the Greek manuscripts, all of which combines to cast doubt on Mark’s having written anything beyond verse eight, there are a number of the oldest versions (or translations) that do not contain the verses in question. Among such are ancient Syriac, Armenian and Ethiopic versions. No wonder that the noted manuscript authority Dr. Westcott states that “the verses which follow [9-20] are no part of the original narrative but an appendage.”
Supporting this testimony of the Greek manuscripts and versions are the church historian Eusebius and the Bible translator Jerome. Eusebius wrote that the longer ending was not in the “accurate copies,” for “at this point [verse 8] the end of the Gospel according to Mark is determined in nearly all the copies of the Gospel according to Mark.” And Jerome, writing in the year 406 or 407 C.E. said that “nearly all Greek MSS. have not got this passage.”
Quite pertinent here is what the New Catholic Encyclopedia (1966), Volume 9, page 240, has to say about these verses: “The manuscript tradition indicates that the Gospel originally ended at 16.8, but that the longer ending that is incorporated in the Vulgate was later added, becoming widely accepted in the course of the 5th century…. Its vocabulary and style differ so radically from the rest of the Gospel that it hardly seems possible Mark himself composed…. Mark 16.1-8 is a satisfactory ending to the Gospel insofar as it declares Jesus’ Resurrection-prophecy to be fulfilled.” Yes, Mark’s style is plain, direct; his paragraphs are short and the transitions are simple.
There is also the matter of vocabulary. There are words used in verses 9 through 20 that do not appear elsewhere in Mark’s Gospel, some words that do not occur in any of the other Gospels, some that do not occur elsewhere in the Christian Greek Scriptures. These verses consist of 163 Greek words, and, of these, 19 words and 2 phrases do not occur elsewhere in Mark’s Gospel. Or, put otherwise, in these verses there are 109 different words, and, of these, 11 words and 2 phrases are unique to these verses.
But most conclusive of all that Mark could not have written these verses and that they are no part of the inspired Word of God is their content. As has already been noted, there is no evidence that Christ’s followers were to be able to drink deadly poison without being hurt, as stated in verse 18. Even in the matter of handling snakes it is very apparent that those handling them do all they can to keep the snakes from biting, and they handle them only for five minutes at a time.
Further, these questionable verses state that the eleven apostles refused to believe the testimony of two disciples whom Jesus had met on the way and to whom he revealed himself. But, according to the account in Luke, when the two disciples found the eleven and those with them, these said: “For a fact the Lord was raised up and he appeared to Simon!”-Luke 24:13-35.
So in view of all the foregoing it can be concluded that Mark 16:9-20 is not part of God’s inspired Word, and that for the following reasons: (1) These verses are not found in two of the oldest and most highly regarded Greek manuscripts as well as others. (2) They are also not found in many of the oldest and best Bible translations or versions. (3) Such ancient scholars as Eusebius and Jerome pronounced them spurious. (4) The style of these verses is entirely different from that of Mark. (5) The vocabulary used in these verses is different from that of Mark. (6) And, most important of all, the very content of these verses contradicts the facts and the rest of the Scriptures.