Should threats of destruction be the driving force behind saving the souls of men? I don't think so. Force is a very poor motivator for actual change...you are more likely to get temporary external change, and no real internal change, which I imagine God really dislikes. What Christ did himself, and what I think real Christians should emulate, is say that "Yes, punishment awaits the wicked. But you can do something today that will save you from your self-chosen death and annialation. Christ is the payment for what you have done in the past, and you can change your nature from Dark to Light by accepting his gift, and choosing every day to try to do the right things."
It is wrong to say, "Ye are Dammed to Hellfire for failing to Blindly Accept Parable as Fact!" It would be more in God's Kingdom to say, "Humans tend to choose evil things that feel good, but you can be saved through the sacrifice of Jesus Christ and remade anew!" If you were outside the Faith, which message do you think would win more souls?
What is usually the goal of punishment ...
1. To teach the sinner a leason ... well hell is forever
So even if the sinner learns his lesson ... so sorry Charlie your here forever (I don't buy it)
2. To teach others what will happen to THEM if they don't do as they are told (re: my post about fear and intimidation)
My personal guess ... a sinner is put back here (or some other inhabited planet) to learn more till they get it ALL right.
BUT then again we all may just be parts of just one big consciousness ... each learning their own individual parts to be assimulated within the collective consciousness ... after all is not "God" all knowing ...