Here is the email that I sent (I've edited it a bit for clarification):
It seems that there are two very different directions that this could be taken. It depends on what is believed to happen at the conclusion of the "punishment" in hell: Annihilation or Salvation?
Is Annihilation An Option?-
Scriptural problems- Providing more than a single passage to contend with might be overwhelming, so Matt 25:31-46 (46 specifically) would be my pick for dealing with annihilation, if I had to choose only one. Jesus uses the same modifier ("eternal") for "punishment" as He does for "life". If we affirm that Jesus meant to communicate that "life" does not come to an end, then we must also affirm that He meant the same for "punishment". If we affirm that He meant that "punishment" comes to an end, we must also affirm that He was telling us that "life" also comes to an end. If the person affirms Matt 25:46, then annihilation is either experienced by none or experienced by all, there is no middle ground.
Philosophical/theological problems- Two points. First, the length of time it takes to commit a crime rarely has anything to do with the time of the punishment (murder and theft are the most obvious that come to mind). In fact, the length of time for the punishment tends to extend dramatically if premeditation (extra time) was involved. Second, Hell is not where we go because we did something bad. We go there because we do not wish to be with our Creator (which just happens to require that we come on HIS terms, not ours- which is really best anyways, because we would drive ourselves nuts worrying about whether we were "making it" or not- spiritual OCD is not pretty). Since the length of the punishment is not dependent on the length of the crime, the time must be determined by some other means. One option is that the length of time in hell is equal to the amount of time we would spend with our Creator for choosing Him: equal to how much time we would spend without Him if we decided to not choose Him. I would then refer to the above scriptural evidence above to determine what orthodox Christianity believes this length of time is (eternity or nothing).
Is Salvation After Punishment An Option?-
We have to go with two passages. If a person rejected Christ in this life, John 14:6 would require the option that people are still able to accept Christ after their death (since good works can't get you salvation- no early parole from hell for "good behavior"); however, coming from a position of biblical inerrancy (specifically that no two scriptures may contradict one another), Heb 9:27 stops that option in its tracks (verse 28 completes the thought started in 27 and affirms the idea that salvation is through Christ alone). If the person affirms both John 14:6 and Heb 9:27 (inerrancy is not necessary, just affirmation of these two), then there is no chance for salvation beyond the physical life- and if hell is not eternal, then he must opt for annihilation for the unsaved and the saved.
How would he interpret these scriptures if hell is not eternal?
Even if salvation after punishment is accepted, annihilation of all is the conclusion (if Hell is not eternal, neither is Heaven). This falls by the same critiques as annihilation given above (both Scriptural and philosophical).
Emotional/moral problem of both positions-
Remember his appeal to morality in judgment of God sending people to eternal punishment? You can now appeal to his morality. Would he annihilate those who accepted Christ? Is it right, loving, or just for God to annihilate those who accept Jesus Christ: ultimately facing the same destiny that the unsaved do? If so, he must defend that position philosophically, morally, and emotionally (and scripturally, but only if he still wishes to say that this god he's condemning is actually the God of the Bible).
I wrote a piece about hell last year that might address any bad experiences directly related to Church members focusing on the doctrine of Hell: http://lukenixblog.blogspot.
Here are a couple articles from PleaseConvinceMe.com about Hell: