This is goddamned brilliant, and if not for the bump I may have not dug it up. Thank you, bump fairies!
I don't exactly feel capable of contributing to this in much of a meaningful way, but I do have an example to add. One thing I think hasn't been brought up in this thread is that strong nihilism, as OP describes it, is not only tied to religion in the 21st century. Look at people I'll generalizingly call 4channers, where whether or not they browse 4chan is irrelevant. They don't blow things up for their beliefs (they just commit school shootings sometimes) but they think society as it stands now is disgusting and worth purging. They lock themselves away, with or without a circle of like-minded people on some website or another, where they form echo chambers for their hateful beliefs. They have a morbid fascination with gore porn and degradation of women - in fact they blame what they call feminism for ruining the world (see: MRAs who don't help men, but just shit on feminists). There was (is?) a whole movement cheering on Ebola (with a cute moe mascot to boot) to wipe out the world, or at least Africa, because this would somehow usher in an opportunity to rebuild the world as a better place. And it's all the Jews' fault.
I used to browse the chans a lot, still do sometimes, and I sure know that the "destroy everything" mentality used to appeal to me, in the darkest days. It seemed to be the only alternative to the toothless, coddling, moderate ways of mainstream society. But then I learned better. And Discordianism sure helped.