Hilbert's Hotel

Supralapsarian Calvinism is sometimes classified as a felix culpa theology. Conversely, you have atheists who say, Why did God create Satan, knowing what would happen? 

Suppose Adam and Eve never fell. What would the world be like? Would it be better, worse, or both better and worse?

Minimally, Adam's posterity wouldn't die of old age. Perhaps, if Adam and Eve ate from the tree of life, their immortality would be transmitted to their posterity. Or perhaps their posterity would need to eat from the tree of life. Or perhaps, as they colonized the earth, they'd take seeds from the tree of life and plant it elsewhere. 

Or maybe God would simply confer immortality on Adam's posterity, apart from the tree of life. It's unlikely that fruit from the tree of life had chemical properties that conveyed biological immortality. How is that naturally possible? Rather, it's more likely that God simply attached a blessing to that object. 

In theory, Adam's posterity might still be vulnerable to death by causes other than senescence. Perhaps God might providentially protect them from death by other causes. Or perhaps God would let them die, but miraculously restore them to life.

It seems unlikely that an intermediate state would exist in an unfallen world. In a fallen world, the intermediate state exists because people die at different times over the millennia, but at the Parousia, death will cease, and all the dead will restored to life all at once. (According to amil eschatology. Premil eschatology is more complex, but the net effect will be the same.)

But in an unfallen world, there wouldn't be that cutoff. So there wouldn't be any point in people dying, then passing into an intermediate state. 

The upshot is that in an unfallen world, the human race would continue to reproduce until it reached an optimum population level. In theory, that might be confined to the garden of Eden. If so, that would be a small population.

Or perhaps Adam's posterity would outgrow the garden and proceed to colonize the more hospitable regions of the globe. But to avoid the detrimental effects of overpopulation (e.g. famine, starvation), it would have to plateau. Suppose at that point God made the women infertile. 

Reproduction would terminate with a stable, unchanging population. However many generations of Adam's posterity until it hit the optimum population threshold. That would be the last generation. Frozen in place. Further procreation would be unnecessary to maintain a replacement rate, since no one would die–or if they died, they'd be restored to life. 

That would be a good world. Better in some respects than a fallen world. However, the overall population would be far smaller. An absolutely static, invariant population.

One fringe benefit of mortality is that it frees up time and space for far more humans to exist. Some of them are hellbound but some of them are heavenbound. Yet the heavenbound humans wouldn't exist in a world where there's a final generation once reproduction reaches the optimum population size. There's no more room for additional generations. The cutoff comes early in human history.

In one respect, a fallen world is worse because it contains hellbound individuals. But that's offset by the greater number of heavenbound individuals, since they don't have to coexist at the same time and place. Because they exist diachronically rather than synchronically in the same place, procreation can continue indefinitely. 

God might still decree a terminus, but it will be very far out compared to an unfallen world. The cumulative population will be vastly larger. Eventually, they all exist simultaneously, but not at the same location. 

Heaven is more capacious than Hilbert's Hotel. Never runs out of guest rooms. Always a vacancy!