Did Mark Write Mark 16:9-20?
Good Christians disagree on this, so don't make it a test of orthodoxy. The point is that we have the evidence to examine and debate, meaning that the text is trustworthy (a lack of debatable evidence would imply collusion and tampering). Still, the evidence seems to point to Mark's Gospel ending on v. 8. Here are a few resources I used in preparation for this topic. They may help you to better understand the issue. The first is a section from the MacArthur Study Bible: The external evidence strongly suggests these verses were not originally part of Mark’s gospel. While the majority of Gr. manuscripts contain these verses, the earliest and most reliable do not. A shorter ending also existed, but it is not included in the text. Further, some that include the passage note that it was missing from older Gr. manuscripts, while others have scribal marks indicating the passage was considered spurious. The fourth-century church fathers Eusebius and Jerome note...