Why do we not read Mark 16:9-20?
You may have noticed that I have told you not to read Mark 16:9-20. You also may be asking why? It’s in the Bible why is Dan telling me not to read the Bible? Well, yes but the answer is both complex and simple. As you have no doubt seen in your Bible there is a bracket with words in italic that say “Some of the earliest manuscripts do not include 16:9–20”. So yes I am telling you not to read 16:9-20 because it is not part of the original text, therefore it is not scripture.
What this means is Mark 16:9-20, was added later after Mark wrote the Gospel. Someone at some point found a copy of Mark 16:9-20 and thought it should be added in. *Queue dramatic music* and this person was someone who worked on the original 1611 King James Version (KJV) of the Bible, which is the most famous bible and most used translation of the Bible for hundreds of years. This version of the KJV is not the one we have in our pews at church. Since it was so widely used and read for so long, bible printers do not like to take Mark 16:9-20 out of their printing of the Bible because so many people are used to it being in there. So they compromised by putting a note saying “Some of the earliest manuscripts do not include 16:9–20.” So in the end Mark 16:9-20 is not part of the original text of the Bible so I am encouraging you not to read it.
If you want a more scholarly answer please see this article from JTS.