I saw the other thread briefly. I don't think there is much of a discussion. "Death" is simply a loss of life. And as one sees it, there is biological life, there is a meaningful life, and then there is the divine life. Death does not lead to non-existence. We know that when one describes death, one can describe a certain type of "separation." It's not wholly accurate though. One can speak of biological death as "separation" of "soul and body" or a hopeless life as a separation from family or a depressing "life". But can you say the same about divine life? Can one truly separate from God. Perhaps, it's an "attempt at separation" that can explain "death." But more accurately, death is a disease. We know that in biology, certain biochemical processes continually fail, and this leads to the weakening and aging of the body. As the failures accumulate, the process of death increases. Likewise, a death to a meaningful life is a process: loss of job, family deaths, no children, divorce, community ostracizing, etc. All leads to a depressing life in someone. Then there's the divine death, a constant and perhaps consistent refusal of God's grace working in your life.
Now, when one points to death, one can get a sense or feeling that we can cease to exist. If you are someone who has no religious beliefs or any spiritual beliefs, you are inclined to believe only what science teaches, that we do indeed cease to exist after death. A depressed person may feel that he doesn't even exist in society and wishes he may have never been born. And then the theological argument made by a particular person: that because we did not exist before, and that we were made from non-existence into existence by the grace and power of God, we can return to non-existence by our refusal of the grace and power of God. True, one can get a logical deduction from St. Athanasius' "On the Incarnation" to conclude this, but he forgets St. Athanasius' other quote about God's love:
It would, of course, have been unthinkable that God should go back upon His word and that man, having transgressed, should not die; but it was equally monstrous that beings which once had shared the nature of the Word should perish and turn back again into non-existence through corruption.
The solution to this problem of non-existence was the Incarnation of the Word. If then the solution was to not allow their natural "non-existence" to take place, then wouldn't the Incarnation, according to people who believe Hell is a state of utter non-existence, a failure? Why should God have created them in the first place if He knew the end result was of no avail? Unless one is to believe that God is nothing but a Life Force, and forgets about the personal aspect of God, that it is possible to have a relationship with Him. All too often, we mistake theosis for a God that is impersonal, and those who do good and bad will experience the same God with different effects, but we forget that God is a personal God; despite our weak natural tendencies, he pursues compassionately our salvation. Otherwise, this "impersonal force" should have annihilated just about each and everyone of us on this earth with whatever the slightest mistake we might do.
Souls can lead to "non-existence", but according to St. Athanasius, it is against God's good personal nature that He would allow humanity to do so. Therefore, death is in a sense a disease and a loss in humanity, and it is at best an attempt at separation and non-existence, but it is also something that God Incarnate destroyed and will not allow to happen to all people even those in the divine fires of Hell.