Sheen's comments were never convincing to me because myths can very quickly spring up around a strong personality, so while a few of the earliest disciples may have been either liars, lunatics or followers of God, that is not even necessarily true of the gospel writers.

Or another way of putting it: if the gospels are truly 4 witnesses accurately reporting what they saw, then Sheen's arguments hold true, but considering that it's likely that Mark was not written down until at least 30 years after the events described in it, it would take the presumtion of divine intervention for that to be the case even assuming that the authors were completely honest.