Apocalypse, in the original Greek (ἀποκάλυψις) refers to an uncovering of hidden knowledge about the true nature of the world, hidden from humanity. In Christian theology, this doesn’t generally occur until the End of Days, when all is revealed and the divine plan becomes fully manifest. Usually, this is an unpleasant sort of upheaval, as all great truths tend to be.
As to zombies, if you’re not yet familiar with the concept of a philosophical zombie, here is an excerpt from the Stanford Encyclopedia of Philosophy:
Zombies in philosophy are imaginary creatures used to illuminate problems about consciousness and its relation to the physical world. Unlike those in films or witchcraft they are exactly like us in all physical respects but without conscious experiences: by definition there is ‘nothing it is like’ to be a zombie. Yet zombies behave just like us, and some even spend a lot of time discussing consciousness.
It’s got to be annoying discussing consciousness with someone who doesn’t actually possess it,but I’ll leave that to one side for the moment. For now, I just need the idea of a p-zombie to introduce the possibility of a certain possible world, call it P-zombieworld. In that world, God exists, but every human being who does not come to freely love God in the sort of way that leads to salvation is not actually a human being in the usual sense, but rather a simulacrum thereof with no subjective experience whatsoever. In our world (according to commonly held Christian doctrine) some number of humans end up suffering some sort of horrible fate because they fail to respond freely to God in a salvific way.
The classical theist can now consider two possible worlds:
PZ-world) A world that looks exactly like the world we perceive, except that everyone who fails to freely accept divine salvation is a Philosophical Zombie.
RW-world) A world that looks exactly like the world we perceive, and it turns out that all apparent humans are actual subjects and not merely simulacra thereof. This is what we usually think of as the Real World.
The question for the theodicists and apologists is why an all-powerful and generally benevolent being would choose to instantiate RW-world instead of PZ-world. I cannot think of any reason myself, but please feel free to ask your Christian friends and pastors. I sincerely look forward to their feedback.