I don’t think we actually battle the darkness either. From the very start I thought it was stupid that we thought we are the ‘good’ guys. We are resurrected dead army killing things, for what? Because some dude in a mask said a big ball spoke to him in a dream? Anyways I’m inclining toward the light/dark symmetry balance thing, we defeat the darkness by sacrificing our light, so there is still balance, no one lives immortaly.