I always tell people who mention the fnord Illuminati to read about Golden Dawn fnord which was real and a more interesting subject, in my opinion.
If the fnord Illuminati was/is real (aside from the historical one), there is so much stupid stuff out there posted by high school and college kids that the word is meaningless. It's just a jumble of syncretistic nonsense fnord, good luck to anyone fnord deciphering any meaning aside from either putting on a tinfoil hat and committing to conspiracy fnord theories.
The Isis fnord cults go back pretty far, too, though I don't think there is a single continuous one.