In a long review of Zeitgeist - The Movie, Jay Kinney on the Tech/Culture site boingboing in August 2007 notes that the video's worldview is that:

Religions in general, and Christianity in particular, are primarily systems of social control. 9/11 was an inside job and the destruction of the WTC twin towers and building 7 were aided by controlled demolition. And finally, International Bankers, through the Federal Reserve and the Council on Foreign Relations (CFR), control our money and our future, leading to, ta da, the coming One World Government and the microchipping of everyone.

The nefarious International Bankers meme has been propagating itself since at least the mid-1800s and has long been a mainstay of radical right-wing circles where it has often overlapped with mutterings about Jewish cabals….The over-all temper of the video is rather like the John Birch Society on acid, with interludes by Harry Smith.

In the orbit of the John Birch Society, the phrase international bankers is avoided and replaced with the phrase “The Insiders.” The Birchers trace the conspiracy back to the Illuminati/Freemason conspiracy theory first popularized in the late 1700s.

In the late 1800s, several populist authors pursued the idea that British speculators manipulated the price of gold, which affected paper currency at the time. A common image was that of an octopus. Who was the head with tentacles reaching out across America depended on the author. This easily slid into antisemitic interpretations with the Rothschild family at the head.

The most infamous source of false allegations of a Jewish banking cabal is the Protocols of the Learned Elders of Zion.

The public circulation of the Protocols grew out of propaganda intrigues of the secret police of Czarist Russia in the late nineteenth century. The main Russian print source for the Protocols first appeared as an appendix in The Big in the Small, and Antichrist as a Near Political Possibility; Notes of an Orthodox Person by Sergei A. Nilus, published in 1905 but republished to wider audiences in 1911, 1917, and 1918.

The text purports to be secret minutes of meetings of a Jewish ruling clique conspiring to take over the world (a claim that should be unnecessary to point out is a bigoted falsehood.). The Protocols incorporate many of the core conspiracist themes outlined in the earlier attacks on the Illuminati/Freemasons and overlay them with antisemitic allegations about anti-Czarist movements in Russia. The Protocols reflect the same themes as other, more general critiques of enlightenment liberalism by those supporting church/state oligarchies and other anti-democratic and theocratic forms of government.

Three publications that followed are of particular interest because they trace a transitional arc that starts with the theme of money manipulation, jumps to war as a form of manipulated internationalist politics, and then jumps back to money manipulation.

The Reign of the Elders (Gold, Gold, Gold), is a short book by an anonymous author that starts with the Protocols, moves through the Rothschilds, and ends up with Roosevelt’s “Jew Deal.” It was published before WWII.

The pseudonym “Cincinnatus” took the same basic arguments and wove them around the theme of Jews plotting War, War, War, to help an England controlled by Jews.

E.C. Knuth’s, Empire of “The City”: A Basic History of International Power Politics was the post-war publication that took the same theme and returned it to focus on financial manipulation by Jews.

The result was the popularization of the idea that the Rothschild family and other Jews controls the British monarchy, City of London financial institutions, and through them, the U.S. government and economy. The Lyndon LaRouche network later adopts this claim, while removing the more obvious antisemitic references after being criticized for antisemitism. Some on the Political Left have picked up these claims and mindlessly repeat them. T

he bulk of published material pushing this antisemitic line, however, comes from the Political Right.

Who is really behind the vast timeless conspiracy? Is it the Freemasons, the Communists, or the Jews? The Rothschilds or the Rockefellers? Is the real control group the Council on Foreign Relations, the Trilateral Commission, or the Bilderberg banking conference? The scapegoated group varies by the sector on the U.S. Right doing the construction of the frames and narratives. These distinctions on the Right really matter, both politically and analytically, writes professor Martin Durham.

Phyllis Schlafly blamed the conspiracy on the “Secret Kingmakers;” which to Schlafly meant the Rockefellers AND the Bilderbergers, but NOT the Jews (Schlafly, 1964).

Author Revilo P. Oliver, a leader of the John Birch Society, was purged by the Birchers after giving a speech where he challenged the organization to come right out and admit it was the Jews behind the conspiracy. Another migration moved L. Fletcher Prouty (Col., U.S. Air Force [ret.]) author of The CIA and Its Allies in Control of the United States and the World, from the standard Birch Society analysis of liberal treachery to a place where Prouty had his book republished by a Holocaust denial outfit at the time controlled by Willis Carto.

If you compare the allegations against the Jews in the Protocols of the Elders of Zion they are remarkably similar to the allegations hurled by contemporary right-wing demagogues at liberals, leftists, and President Barack Obama and the Democrats.

It is in this right-wing milieu of conspiracy theories and venomous vilification that Loughner picked his target.