The root of Christian belief is that we each need to make a choice between resurrected life eternal in Heaven - or not.
This choice is very simple indeed: do we (personally) want this, or not?
Of course, we first need to understand what it is that we are choosing (or rejecting) - but really, that is the only difficulty; and I presume that after death we will be shown - or rather we will come to know directly - exactly what it is we are being offered by Jesus Christ.
So for God, the Creator, the essence of human life is very simple, simple enough to be comprehensible to a child - and God's desire is for each of us to understand life in its absolute simplicity.
Even with complete clarity and grasp of the nature of resurrected life everlasting; there are some that will reject it - and presumably these clear-rejectors include (but are not confined to) the devil and his leading demons.
For the devil and his demons and servants; the opposite of clarity and simplicity is the desired state
The devil wants to induce a permanent and overwhelming impression of complexity, leading to a deep confusion - so that when we are offered the choice of resurrection, we cannot see it for what it really is.
This describes the distinctive evil of the modern Western mainstream world. It is a world in which complexity and confusion has reached levels many-fold beyond that attained in any previous society anywhere. A world in which fundamental - and correction-resistant - confusion is endemic, and still increasing. A world in which the powers of purposive evil have attained unprecedented sway.
There is even a large category of people who describe themselves as Spiritual Seekers; and who remain seeking for year after year, decade after decade, preferring to stay enmeshed in complexity and confusion; rather than recognising The Choice, and making their choice - one way, or the other.
As I have mentioned before; I think that God's desire to make this choice clear and simple may be one significant reason behind the increased lifespan of modern Western Man, and the increasing levels of 'dementia', delirium and other mental impairments.
For a typical modern Western Man; the progressive simplification of advancing senility may be exactly what he most needs in order to grasp life in its ultimate clarity. Illusions and wishful thinking, active sins and the lies we tell ourselves are demolished incrementally - until the soul finds itself in a body and/ or mind that are alive... but little more.
This may be, for some people, the best way to bring them to a recognition of the Human Condition, and The Choice. In which case a long life or declining quality (as measured on an axis of pleasure and its absence) may be for the long-term benefit of the person who experiences it.
Whether this is actually true in a given instance will depend on that specific individual - and may be knowable only to him... plus perhaps those who love him.
The end of the process would come after death, when that individual is brought to the point of decision: to follow Jesus through death to eternal resurrected life in Heaven - or not.
And I believe that we who remain alive for the present may be able to know the outcome of this decision for those we love; we may learn what happened after death to those we love by means of prayer or meditation.
Naturally, this would never be anything we could 'prove' to anybody else (nor should we attempt to prove it); nonetheless such knowledge could be of the very greatest importance to our-selves, here-and-now.