Possible influences of Bree's religion

Throughout the series, Bree's religion has been the focus of much speculation. the Creators have identified Bree's religion, the Order of Denderah, as something completely fictional. Over the course of the series, fans have speculated about the influences that real-world cults, secret societies and religions have had on the creation of the Order.

Cults
Daniel has called Bree's religion a cult. The word cult generally has a negative connotation and often suggests fundamentalism, extremism, the withdrawal of cult members from society and even brainwashing.
In the video Learning Egyptian, Gemma says that Bree's religion is not a religion at all, but rather a secret society called the Order. Most people would consider the Order to be a cult, because it is far outside the mainstream and is willing to go so far as to murder dissidents.
While the Order bears most of the trademarks of a cult, it does not appear to be modeled after any particular real-world cult.

Illuminati
The Illuminati generally refers to a shadowy conspiratorial organization which is reputed to secretly control world affairs. The Illuminati are believed by some conspiracy theorists to be an organization attempting to take over the world with a single, fascist government. The Illuminati supposedly derives from very old secret societies.
However, there were historical Illuminati. The Illuminati, also called the Bavarian Illuminati, was a free masonic group started in Germany by Adam Weishaupt. The organization was very secretive and, due to paranoia by outsiders, was accused of many conspiracies due to the fact that no one knew anything about the inner workings of the Order. However, among the intellectual elite there were Illuminati sympathizers who claimed that Weishaupt's organization existed to spread morality to the common man. One such sympathizer was none other than the president of the United States, Thomas Jefferson, who said of Weishaupt:
"As Wishaupt lived under the tyranny of a despot & priests, he knew that caution was necessary even in spreading information, & the principles of pure morality. He proposed therefore to lead the Free masons to adopt this object & to make the objects of their institution the diffusion of science & virtue. He proposed to initiate new members into his body by gradations proportioned to his fears of the thunderbolts of tyranny.
This has given an air of mystery to his views, was the foundation of his banishment, the subversion of the masonic order, & is the color for the ravings against him of Robinson, Barruel & Morse, whose real fears are that the craft would be endangered by the spreading of information, reason, & natural morality among men."
Some fans believe the Order of Denderah has similar characteristics to the Illuminati. The Order of Denderah, according to Gemma, is an ancient secret society that traces its roots back to ancient Egyptian times. Like the Illuminati rumors, the Order of Denderah has members placed in many positions of influence. Evidence of this was given by Bree when she stated that politicians and police officers often met at her house with her parents over Order business. Aleister Crowley is sometimes mentioned as having been involved with Illuminati activities.

Freemasons
Freemasonry is a fraternal organization whose membership is held together by shared moral and metaphysical ideals and—in most of its branches—by a constitutional declaration of belief in a Supreme Being". Freemasonry does not attempt to make all members one religion, but rather attempts to make all men good religious people, whatever their religion may be.
Freemasonry works upon a degree system. Through successive degrees, a person is lead from a state of total cluelessness through initiations which operate as plays, illustrating morals and aspects of character which are considered desirable in many of the world's major religions as well as society in general. After the initiation, the individual is presented with study material by which he can identify the symbolism of the initiation and decide for himself what life lessons are communicated to him through the ritual.
Freemasonry has come up in discussion of the lonelygirl15 series because it was mentioned that Bree's religion is not a religion at all, but an order. Many fraternal orders, occult or otherwise, actually borrow in some way from Freemasonry since it is the oldest surviving fraternal order in the world. The list of organizations that borrow from Freemasonry include the Ordo Templi Orientis, the Golden Dawn, and the A.: A.:, which were all organizations that Aleister Crowley had membership in. They also include orders such as the Knights Columbus which was actually put forth as an alternative to Freemasonry by the Catholic Church. So, there is a chance that the Order that Bree's family is involved with somewhat resembles the structure of Freemasonry.

Knights Templar
The Knights Templar were an order of knights commissioned to protect pilgrims on their travels in the Holy Land during the Crusades. They were an organization of warrior monks, having taken vows of celibacy, poverty, obedience, and piety. As a part of their commission, they answered to no one but the Pope himself.
The Knights Templar were lated disbanded by the Pope in the 1300s. Freemasonry (which started in England) also claim lineage with the Knights Templar and it is speculated that the Illuminati, which was a free masonic order, owed its origins to the Knights Templar as well. At the time, the Templars were accused of many crimes, including worship of a god known as Baphomet. It is now generally believed that the Templars were the victims of unfounded persecution.
As Bree's religion is also a mysterious Order, a connection has been theorized. It was briefly believed by some that the picture on Bree's room was once of a Baphomet, though this later proved not to be the case. Gemma says in the video A Watcher that the watchers operate a bit like an Order of Knights. Some believed she may have been referencing the Knights Templar.

Church of Satan
According to Wikipedia "Anton Szandor LaVey (11 April 1930 – 29 October 1997) was the founder and High Priest of the Church of Satan as well as a writer, occultist, musician, and actor".
Satanism is not about worshiping the "devil" as described in the Judeo-Christian Bible, but rather embracing the true humanistic/animalistic sense of mankind. LaVeyan Satanists do not believe in any deity.
Satanists do use the Rabelais statement "Do what thou wilt" but it differs from the Thelemic concept of "Do what thou wilt" rather dramatically. Whereas the Thelemic concept sees a person's will in that statement to be a person's "higher" will, divine purpose, or "nature", Satanism sees "will" more in the mundane sense of the word.
Satanic rituals that follow LaVey's format do not include the use of blood or literal sacrifices. Satanic rituals are thought of by Satanists as an emotional/psychic decompression chamber.

H.P.Lovecraft