The heart of Athanasius’s account of the Incarnation is the thought experiment of the divine dilemma. Picture God in the face of human sin. Since human beings are in no position to fix the position they’ve put themselves in, His options seem to be limited to either ignoring the sin in a sort of divine “do over” or abandoning human beings altogether, but neither course is consonant with his nature. The Incarnation thus presents itself as the only way to act in the face of the dilemma. But this divine dilemma can be seen as a second one – the first dilemma was whether to create human beings at all.
On the one hand, human beings are necessary given the decision to create anything at all. Only a complete entity can be an object of intention, and rational animals are necessary for the completion of the universe since they are a distinct ontological strata. It is only through human beings that spirit becomes intrinsic and essentially one with the universe, and only through human beings that matter can be made holy and offered to God or a person can arise by way of generation as happens within God himself.
On the other hand, when we descend from the pristine abstraction of metaphysics to the concrete details, creating human beings starts looking like a really, really bad idea. A rational animal has to follow the dictates of reason even while strong, irrational desires are intrinsic and essential to who he is, which will make his inner life one of conflict and turmoil. The human spiritual drive to freedom will be constantly impinged on and frustrated since such persons will lose much of their life to sleep and a large portion of what’s left to the things necessary to merely survive. As material, they’ll enter into a world of sheer unpredictability, chance and organisms that compete for resources, all of which will give rise to disease, disaster, animal maulings, crop failure, and a hundred other sorts of bad luck. Since the human person has to be natural, and natural things arise in large part by selection, bad luck will enter into his very existence: and so our spines ended up poorly adapted to our posture, our hips were poorly adapted to birth, our desires for fat and sugar are poorly adapted to the contemporary world, our cognitive machinery was poorly adapted to any life outside one of nomadic subsistence, etc. Given the strange way human beings learn, we have to do things for a long time before we enjoy doing them, which seems like a recipe for frustration, failure, and mediocrity.
God’s solution to this dilemma was a supernatural gift called original justice. The name isn’t familiar because the gift was somehow lost. The loss is what Athanasius takes as a given when he formulates his divine dilemma.