The Illuminati was a secret society founded in Bavaria by irreligious scientists, educators, artists and forward-thinkers in general. They were stomped out by the King and the Roman Catholic Church in the 1700s.
i explained this somewhere before, the Illuminati is an excuse for "conspirators" to cut themselves off from society because either they don't feel like they fit in or they just dislike everything about it.
don't get me wrong, i'm sure the symbols and stuff are probably true, but surely they weren't intentional at the time and if they were then it's just to annoy the conspirators.
i also do believe there could be secret societies we just don't know about. i mean... their secret societies how on earth could we ever know about them? i just don't think they'd be as complicated or as satanic as some conspirators want to believe.