Revelation 1:18 tells us that Jesus holds the keys of death and of hades, and orthodox interpreters regard the phrase 'death and hades' here as merely a form of hendiadys, i.e. it simply means 'death and the grave'.
I'm struggling to see this as a permissible point of view, however, because in all of the New Testament scriptures where the word 'hades' is used, it refers to a places of punishment for the soul after death (Matthew 11:23, 16:18; Luke 10:15, 16:23; Acts 2:27, 2:31).
If there are keys to what is in effect 'hell', does it not follow from this that people can be released from hell? (We would otherwise have to say that Jesus holds a key that doesn't work or which He is not able/allowed to use.) And why does Revelation 1:18 tell us that Jesus holds this key in the first place, if it will never, ever be used?
Perhaps this verse is a little stronger in terms of its support universalism than some may have originally thought.
Yes I first read about this as a reassurance in the book "Hope beyond hell". Although my view of Hades has changed a bit since then, I think the Hades of revelation is more figurative since it is described of being emptied of the dead although there is still a second death, so its traditional meaning as place of the dead would become obsolete. But even after the second death we have the reassurance that Christ is calling all those outside into the gates of the new Jerusalem which shall under no circumstances be closed.
What do others think?