Not long now until the end of the world. It's a something many have become disillusioned by because currently there is political theater with spectacle enough to entertain that part of mental activity that revels in doom.
My own view of the world's end, puts it in the perspective of yearning. As a rule the thesis describes cataclysm followed by renewal. We experience horribleness and then are refreshed by new disciplines, or what the socio-biologists might call "alternate memes."
There are some of us who are so flattened by the base nature of our species they have envisioned the world's end as a sort of cull, during which we are first subjected to trial then some of us are sent shackled into eternity. And this I guess is what is meant by purity.