References to the Illuminati appear in many conspiracy theories as an umbrella network that reaches into all the major institutions and movements of the world - finance, governments, the United Nations, religion, the environmental movement - to control world events.
They are supposed to secretly control all government, all religion, all business, and all backroom global decisionmaking. Such conspiracies often refer to the New World Order and widlely cites lists of supposedly connected dates -such as in Timeline to global governance as evidence of progress towards global control.
Interest in the Illuminati - the ultimate secret group of secret groups - was revived in the 1980s through the semi-fictional writing of Robert Anton Wilson , particularly "The Illuminatus Trilogy", co-authored by Robert Shea."Illuminatus!" was intended to blur the line between truth & fiction, and much of the fiction has entered into popular lore. It is often hard to tell from many websites about the Illuminati if the authors are in on the joke or not. Some website authors on the subject are clearly not kidding. Some are seeking to warn the world about their paranoid fantasies. Others are seeking to manipulate for their own political or religious ends.
The origin of the Illuminati is widely attrributed to Adam Weishaupt, first leader of the Bavarian Illuminati. 
"May 1, 1776, was the most important date in Freemasonry's Luciferic New World Order Plans. On that date an obscure Jesuit-trained professor of canon law at the University of Ingolstadt in Bavaria, Adam Weishaupt, founded a secret society called the Ancient and Illuminated Seers of Bavaria (AISB for short)," as one website describes it.
One fundamentalist Christian site writes of the Illuminati "The worship of this religion is practiced in secret. The dogma and intentions of this religion are hidden by way of symbology. The average person sees the exoteric, outward or literal meaning of the symbols, while the Adept, Initiate or Illumined see the esoteric or hidden meaning of the symbol... When George Bush referred to a "Thousand Points of Light" in his speech in 1991 he was using the symbolic language and was referring to the body of initiates... The average person heard the exoteric meanings of these statements while initiates the world over smiled to themselves, as they understood the true meaning. You see George Bush is a member of the Order of Skull and Bones Society. Bill Clinton holds the 33rd degree in the Masonic lodge. Bob Dole, a Republican, is a 33rd degree Freemason. So it doesn't really matter for whom you vote, you are in effect voting for the Mysteries. These people and many others are all practitioners of the Mysteries and know exactly where the world is going..." 
Many conspiracy theorists and zealots see virtually everyone as connected to the vast global conspiracy -- run by the devil & his henchmen (with the help of Jews, Catholics, Muslims, the Chinese communists, etc.) seeking to unite all world governments and all world religions.
Several groups lay spurious claim to the shadowy Illuminist lineage. The Bavarian Illuminatti did exist at one time as a secret brotherhood, but today references to such an organization are usually used as a fictional construct, or else to spread misinformation, disinformation and propaganda -- a modern day political/religious myth of a global super-secret cabal that manipulates the geo-political environment to suit their own ends. In this respect the lore of the Illuminatti should be regarded as a modern folktale which, like all folktales, contains a hidden moral to the story.
Anyone can make up anything about any group or public figure that they dislike and simply add just enough true "facts" to create the appearance of a conspiracy. They either have their own secret agenda for spreading such suspicions like the Nazis or the fringe pseudo-Christian group cited above. Some are motivated by hatred, fear, and bigotry. Others are simply delusional. Some are both.
Many conspiracy theorists blend a scepticism of power and elites but take unconnected events and unproven links to bolster the view that the Illuminati control world events. Question authority, but question the motives of the questioners too, particularly those who seem to have all the answers or secret uncheckable facts that no one else seems to know about.
- "Robert Anton Wilson", Wikipedia.
- http://www.amazon.com/exec/obidos/search-handle-url/index=books&field-author=Wilson%2C%20Robert%20Anton/103-7373140-0875065 links to the works of fiction by Robert Anton Wilson.
- William H. McIlhany, Summary Early History of the Illuminati Master Conspiracy (a list of works seen as documenting the Illuminati network)
- Illuminati Conspiracy, Order of the Illumined Wise Men (a listing of elements seen as proving the existence of the Illuminati conspiracy theory).
- Brian Desborough