Andrew, some of those very same thoughts have prompted me to seriously consider annihilationism as a solution to the apparent dilemma.

Understanding the proper use of “Gehenna” and the context in which it was used in the first century is crucial to the conversation in my opinion.  In his book “The Fire That Consumes: A Biblical and Historical Study of the Doctrine of Final Punishment,” Edward Fudge wrote:

The valley bore this name at least as early as the writing of Joshua (Josh. 15:8; 18:16), though nothing is known of its origin. It was the site of child-sacrifices to Moloch in the days of Ahaz and Manasseh (apparently in 2 Kings 16:3; 21:6). This earned it the name “Topheth,” a place to be spit on or abhorred. This “Topheth” may have become a gigantic pyre for burning corpses in the days of Hezekiah after God slew 185,000 Assyrian soldiers in a night and saved Jerusalem (Isa. 30:31-33; 37:26). Jeremiah predicted that it would be filled to overflowing with Israelite corpses when God judged them for their sins (Jer. 7:31-33; 19:2-13). Josephus indicates that the same valley was heaped with dead bodies of the Jews following the Roman siege of Jerusalem about A.D. 69-70…Josiah desecrated the repugnant valley as part of his godly reform (2 Kings 23:10). Long before the time of Jesus, the Valley of Hinnom had become crusted over with connotations of whatever is “condemned, useless, corrupt, and forever discarded.” (Edward William Fudge, The Fire That Consumes [Houston: Providential Press, 1982], p. 160.)