@Jack of Hearts,
What you must remember my friend is that when Shadrach Meshach an Abednego refused to bow down to the idol in Babylon, they were tossed in the furnace. Remember they were not harmed, there was an angel walking around in the furnace with them keeping them from harm. So spirit creatures are not harmed by fire, and have the power to protect humans from it. Would this not render a literal hell rather impotent?
If the fire was not literal, but symbolic, what do you think fire would be symbolic of if not destruction?
If all your sin is paid for at death, why is further punishment required?