The Eternal Battle Between Good and Evil is basically the continual conflict between compassion and selfishness.
We all have the capacity for both, but which one dominates?
When selfishness rules, then the world becomes a more dangerous place, a far more unpleasant place to live.
But when compassion is foremost, then pain is eased and life feels like it has purpose beyond just struggling to exist.
Forget personified deities.
Forget an afterlife of heaven or hell.
Forget Karma over several lifetimes
Quite simply, the more selfish everyone is, the more hellish life becomes.