Athanasius repeatedly says that created things, having come from nothing, have an inherent tedency to move toward nothing again. They have to be sustained by God to remain in existence.

No problem with the conclusion that God keeps things in existence. But the notion that things tend toward nothing seems to imply that they have some principle or telos, some “nature,” that is not given by God, something that pulls against God unless he pulls back. But how could that be? Athanasius’ point seems to assume a degree of autonomy in the creation, albeit an autonomy that can only lead to non-existence.