http://www.bimc.org/bimc/oldweb/FAQ.html
This is partly satire and partly true. The Illuminati is not this big, collective group as people would have you imagine. The Illuminati is simply anyone who is "illuminated" or "enlightened". This could range from monks who live in the mountains, hermits, people who are into the occult, a random guy, Freemasons, etc. A lot of people seem to confuse the Bavarian Illuminati as the ONLY Illuminati group. They were simply the first (to my knowledge) to use that name.
When people discuss conspiracy theories they're usually only talking about the ones in powerful places. They always seem to miss the Discordians, the Church of the Subgenius, DKMU, Golden Dawn, monks, and even individual people and other orders. The Illuminati is actually a wide collective spanning many different sects, orders, people and groups. Not all of them are this evil conglomerate out to dominate the planet. Some are quite wise and benevolent and others (such as Discordians, COTSB, etc.) are neither and of course other people in powerful places are out for their own needs.
If the Illuminati was one group out for power then it would have been over a long time ago.