At this point, naysayers are quick to say that I’m building a theology off a metaphor. He was using the term Gehenna—which is the burning the trash heap outside of Jerusalem; he was not using the term Sheol. To which the response is, obviously longer in the last post that Christ added details that had nothing to do with Gehenna and usually with the point that this was something to be avoided because of where it resided and its duration. Plus, Christ was using a metaphor that was already being used by Isaiah 30:33. And one must be careful. The word Hades winds up being used in the New Testament (for example, in the parable of Lazarus and the Rich Man) and the word Sheol in the LXX is translated to that word. Does that mean that Abraham’s Bosom is in Hades? Like I said in the post on Sheol, the word has a semantic range but it definitely has a negative part and a positive part. The fact that Christ gives further details helps us understand what is going on, even if the details are sparse.
The Naysayers would point out that Isaiah was using a metaphor too: for a funeral pyre. The wicked king was dead and was about to be burned. But the point of that passage is not only that the king is dead but that the pyre is prepared by the Lord. Each time that fire comes out from the Lord in Scripture it is to consume. Sometimes it’s to consume an offering. But the rest of the times it is a sign of divine judgment (1 Kgs 18:38). The Lord is deciding something. So why is the Lord setting fire to a lifeless corpse? If the man is dead, hasn’t the point been made? Why is this pyre long prepared? Why does the Lord’s breath come out to ignite it? Simply saying it’s a degrading death doesn’t do justice to what’s going on: God is doing something that he prepared before to a wicked person who deserved it—after they are dead.