Let’s see if we can understand this: If we look at the accuracy of the New Testament documents we see that there’s a 0.3% difference between all the 24,000 manuscripts that we’ve found. Once we eliminate all the copyist errors. Well, this is one of those differences. These last few verses of Mark are missing from most of the earlier copies of the NT documents that we have. This Mark passage also talks about drinking poison and handling snakes etc. Well the truth of the matter is that we aren’t sure if these last few verses were actually written by Mark or were actually a commentary added later by a church father. Note that this does not invalidate any of the other passages because we have 99.7% accuracy of all the rest of the documents. And it does not change the issue about the resurrection of Jesus. All it does is question whether one has to be baptized to be saved. Well I’d say that if this verse scares someone then they should be safe and just get baptized. But remember the thief on the Cross was not baptized (though he technically died before Christ rose but I can’t see why that would be significant). Also most of the rest of the Bible is logically consistent that being baptized does not save you but is merely a symbolic witness to the rest of the world and done in obedience to God.