There have been a flurry of questions lately regarding the interpretation of Matthew 10:28 from various theological positions, primarily from those who do and who do not believe in eternal conscious torment. See here, here, here, and here to start and just follow the bunny trails of answers, comments, and chats if you dare.
Matthew 10:28 says:
And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.
We are told not to fear man because he can only kill the body. The "him" which we are to fear is God because He can destroy both body and soul. If I have understood them properly, annihilationists understand this to be referring to the ability of God to render both the body and the soul of a person (including all of whatever that means) non-existent. In other words there is no eternal destruction process but every aspect of what made that person a person is utterly obliterated at some point in time. Additionally, this non-existence is total, final, and permanent with perhaps even the erasure of that individual from even the "memory" of God. It is allowed that such a one might experience varying levels of pain and conscious torment at the moment of destruction (however long that moment may last) but it is transitory in nature and comes to a definitive irreversible end.
I remember reading in C.S. Lewis (and I frustratingly cannot find the reference, so please help if you can with an edit) that "it makes no sense to talk about the benefit or detriment of non-existence." Presumably this is because every alleged benefit or detriment which might be attributed to existence is unavailable to them...because they don't exist.
For the annihilationist reading Matthew 10:28, what fear is there to hold regarding the possibility of non-existence? Put another way, what is to be feared about the removal of all benefit and detriment related to existence? Or is it the destruction process itself that is to be feared rather than the end result of that process wherein fear also ceases as a benefit or detriment?