Man has free agency, and this is intrinsic and eternal.
Man uses his agency to make choices, but some of these free choices will be sinful.
The work of Christ has wiped us clean from these sins. Now we get the benefits of our good choices, and are forgiven our evil choices. Our prospects are transformed.
Yet, the problem remains of how it could ever be that creatures with free agency could ever cease to make evil choices.
The slate has been wiped clean, and is wiped clean continually; but why would Man ever cease from writing sin over it again and again - even in Heaven?
That there would be no temptation in Heaven is an inadequate answer, since Man would not have fallen if there had been no temptation. The assumption is that mortal life, death and resurrection puts us into a better position than Adam...
The ultimate question is something like this:
How can man be transformed such that he will always choose good?
It must always be a choice, and the choice is (and must be) free; and yet the free choice must always be of good.
Man must become such that he will always resist temptation, will always shun sin, will always choose God instead of pride.
This matter is - I think - almost wholly neglected; and yet I believe the question is valid and vital.
Somehow we must explain how men become good gods - gods who always choose good; and how our mortal life is a necessary part of this process.
This happens; but we lack a clear, simple explanation of how it happens.
The story we tell ourselves of human purpose, meaning and relations with God should tell us how this happens. Yet at present it does not. There remains work to be done...