As a young child, aged about five or six, I quite suddenly became afraid of death. That is, I became afraid of other peoples' death - I became afraid that someone I loved, among my family, relatives and close family friends - would die and be lost to me.
At this point in my life I was not an atheist; but neither was I a Christian. I was, indeed, somewhat hostile to Christianity as it was taught me. And I was (as perhaps all Men are) a natural pagan; therefore I did not love the gods, and I assumed that the gods did not love me; but instead they wanted propitiation, worship, sacrifice. They did not want to be 'asked', but needed to be begged.
Thus I prayed - whenever the thoughts of death came to mind - with desperate pleading and multiple repetitions. I prayed for the preservation of those I loved; that they would not be taken from me and lost from my life.
Death seemed like the greatest disaster that could befall me - but at that point I could hardly comprehend my own death; so the worst I could imagine was to be left bereft, unprotected, in a world of strangers who were probably indifferent and uncaring at best; and some were spiteful, hostile, nasty.
I realized, with perfect truth, that to live within the loving warmth of family was the greatest possible benefit the world had to offer; and that death threatened this happiness and security more - and more irreversibly - than anything else.
In general; I think that these spontaneous and natural beliefs of early childhood are truths - truths implanted by God or known from our pre-mortal lives. Therefore, not only truths about this earthly mortal life; but eternal truths.
...Yet, of course, truths as understood by the mind of a child.
Therefore, our best goal as adults to to return to these spontaneous childhood beliefs, but this time consciously and by choice; and understanding what they really mean in an eternal context.
I now understand my young-childhood fear of death to be representative of the real terribleness of death when (as naturally) understood as an end to mortal life with loss of the self - loss of what makes each person who they are.
It is this legitimate fear that Jesus Christ came to save us from. A child could understand it - and indeed a young child is nowadays more likely to understand what Jesus offered than almost anyone else.
A child's fear comes from the fact that he knows, deep down, that the death of our loved ones in mortal life can only be delayed - and that sooner or later everyone will die. It is indeed, the awareness of death that triggers this stage in childhood.
Spontaneous human thought (among children, and those whose minds are child-like) cannot get further than this the fear of death and the desire to delay death. The child cannot see past the fact of death. Neither, apparently, could the ancient Hebrews of the Old Testament who regarded all Men's lives as terminated in Sheol, nor the Ancient Greeks who regarded all lives as terminated in Hades - both of which entailed loss of the self.
The dead were not the people they had been in mortal life; and so there was no consolation in their persistence as 'ghosts'.
Nonetheless, a Christian knows that he has been instructed Not to fear, that fear is a sin - and this prohibition on fear includes death. So for a Christian the fear of death is just the beginning of the matter - not its end.
As an adult we can and should realize that the best (and only) possible gift to address this childhood fear of death would be that this mortal life would be followed by an immortal life in which were still our-selves, and could (potentially) live forever with those that we had loved in mortal life.
In other words, The Answer to death is: that-Heaven promised by Jesus Christ - that Heaven (I would add) particularly as clarified by more recent, more detailed Mormon revelations concerning the nature of Heaven and the continued existence and importance of the family*.
Unlike paganism; Heaven is not a spontaneous insight of childhood. Its necessity - as the only solution to the problem of death which answers to the desires of a loving young child - could perhaps consciously be derived from the conviction that the Christian God the creator is our loving parent (thus very far from the gods of paganism, and from the abstract deities of some philosophies and religions).
But the Christian Heaven - that is, of resurrected Men living eternally as 'children of God' (ie. as ourselves creative gods) and in familial 'brotherhood' (i.e. in families and divine friends) and knowing the ascended Jesus... such a Heaven could not realistically be inferred by a child. The child would need to be told; and then he might - or might not - believe Heaven was true.
I decided (as child of about six, a while later than the above-described stage) that the Heaven I was told-about was not true, but was made up from manipulative motives...
I would still agree - that Heaven as it was told me (or, as I understood it) was Not true; and that the description had been contaminated by this-worldly motives related to making me behave in certain ways.
Yet I erred in throwing-out the whole idea of Heaven; rather than (as I should have done) thinking more deeply about Heaven, aimed-at discerning how Heaven really was.
I disbelieved in the Heaven that I was told-about - but I should have believed in Heaven as it really is; and I should have made it my life's task to comprehend that that real Heaven offers the only full and satisfying answer to the problem of death.
My suggestion is that others should do the same. You should think upon the idea of Heaven, and how Heaven would need to be in order to answer the problem of death.
Only when you have grasped what Heaven really would answer that problem, have you discovered what it is that Jesus is asking you to believe... Or, more exactly, what Jesus is offering to those who want Heaven.
And you will find that when the problem of death has been answered; then the fear of death - I mean that inescapable existential angst - is indeed cured.
At least, such fear is cured whenever we have Faith and Hope based upon Love (or 'Charity'); and even when we don't experience the cure, we can know that restoration of that Faith, Hope and 'Charity' will drive-out our fear.
*I regard mainstream Christianity as having lost sight of some of these key revelations about the nature of God, Heaven and the Family - which was why I believe that Joseph Smith and some of the other Mormon prophets were inspired to articulate these vital truths in a new, radical, and superior metaphysical theology. This appears in the work of early Mormons and some recent writers - along with other non-essentials and errors; therefore requiring, as always, discernment. But these truths having been articulated was of great value to me. Instead of having to work them all out, I was more easily able to recognize intuitively their truth, beauty and virtue; then (without too much effort) to organize them in my understanding.