There seems to be a hierarchy as follows:
1. Timeless, unchanging eternity percieved all at once - the perspective of God.
2. Eternity experienced serially - the perspective of angels, and Sons of God (i.e. immortal resurrected humans).
3. Unending serial time - the perspective of unsaved souls.
4. Finite serial time, such as humans live in before they die, while on earth.
Christian salvation seems to be the promise of a transition from the fourth to the second category (aka Heaven); damnation is the transition from the fourth to the third category (aka Hell).
A difference between unending serial time and eternity experienced serially is related to the sense of duration.
Unending serial is like time on earth but going on forever, experienced by a disembodied soul (a soul severed from its body).
Eternity experienced serially has no subjective duration, no sense of 'time passing'. Experience is added-to serially, the self is changed and 'updated', but the the resulting state is instantaneously apprehended.
So, a choice before us at the end of finite time relates to either staying the same as you are forever, versus being transformed into a different kind of state (while retaining selfhood).
The temptation of pride is to stay the same and do what you will; to reject what you are and trust you will be made better and do God's will (not your own) requires humility - and Love of God.
On this model, the problem was how to bridge from eternity experienced serially to finite serial time.
The incarnation of Jesus Christ brought eternity into time - fusing eternity and time; and His death and resurrection provided a 'template' for the transition to eternity experienced serially, as a possibility 'from then onward' (as we say who live in time).
I imagine this working somewhat like a morphic field as described by Sheldrake, or a strong attractor in chaos theory -
The above is, like all human attempts to understand reality, a metaphor - maybe helpful, maybe misleading - ignore if the latter.