The Operative is the true believer who, at the end, finds out that the God he's been serving is a false God -- in finding out that the Alliance created the Reavers in their attempts to pacify people and then covered their role in the Reavers' creation up, the Operative discovers that the previously mostly-benevolent Alliance was, in fact, fundamentally corrupt and authoritarian. He becomes the Existentialist who realizes that God is dead but that he still needs to empathize with other people and treat them morally.
I don't agree that it means the Alliance is fundamentally
corrupt and authoritarian, just that it had fallen too much under the influence of corrupt leaders. That doesn't mean it isn't a basically sound system. Even a well-intentioned system can go wrong if the wrong people end up in charge of it (as we Americans know all too well after the past eight years), but that doesn't mean it can't be redeemed.
The whole point of Serenity
, after all, is that the road to hell is paved with good intentions: that the Alliance was founded in order to foster peace and prosperity, but it was taken too far. But the ending of Serenity
suggested that the exposure of Miranda might be the first step toward redemption.
Early, on the other hand, is a Nihilist. He's the man who realizes that there is no God, but takes this as meaning that since nothing inherently means anything, there is nothing wrong with hurting others.
Kind of the opposite of Angel's epiphany: "If nothing we do matters, then all that matters is what we do." I.e., if the only meaning in an action is in the action itself, rather than some cosmic consequence or reward, then it's important to make that action positive rather than negative. I think that's basically Whedon's view of the world.