{Fixed (you're welcome)}
Immanentize the eschaton is a theological term used to describe the act of bringing about the Kingdom of God or Dominion of Heaven in the immediate future; usually translated into American as "trying to cause the end of the world."
Eg., Joachim of Fiore was guilty of immanentizing the Eschaton, and the Protestants have been at it ever since.
In the Illuminatus! trilogy, a history of religious and political upheaval in the last century by Dr. Robert A. Wilson, a the Illuminatti attempts to immanentize the Eschaton by resurrecting a horde of nazi shocktroopers preserved at the bottom of a lake, and killing the attendees of a music festival in the woods in Bavaria. Some broad with a lot of free time on her hands trips hard enough to become Eris, and throws her golden apple (which is becoming dated, if you ask me.) and the nazis all kill each other, or somesuch. And some dolphins make a pontoon bridge across a bottomless lake. It was far out, man.
TLDR[]
==or the Non-Fiction version (read: the god's honest truth)==
Basically Immanentize the Eschaton = End the World.
So basically the Illuminati (i.e. the assholes behind like every organization, social movement, and/or institution ever) are a bunch of hardXcore (read: straight edge) Buddhists and therefore believe life is just incessant suffering punctuated by brief illusions of happiness and free-will, so the best thing to do is just Immanentize the Eschaton (read: end the world.) This has pissed off a lot of hippy free-love Discordians (read: amoral anarchists) who think that in spite (or because (fucking masochists)) of life's suffering it's still worth living...for some reason.
To this end Operation Mindfuck was instituted (ingeniously disguised as an Illuminatus Primus imperative (or is it?) so the unwitting Illuminist dupes actually perpetuate it THEMSELVES (read Cosmic Trigger you ingrates.)) to hopefully confuse, misdirect, and generally throw a wrench in the cogs of the best efforts of the dopeless hopefiends before it's too late (or is it?)
...classic