As any Philosopher of Science will tell you formal theories serve as explanations to observed phenomena, an association between the explanandum - the object of phenomena to be explained; and the explanans - the framework, concept or theory to be used as an the reference point for explanation. Pioneers in philosophy of Science such as Hempel coined this logic inference to the best explanation.
Employing a Meta theory that explains a form of social reality and existence has long been the goal of Philosophers who propagate abstract thinking and rules of logic to define and set the boundaries of ontology and epistemology. In Political Philosophy one often has the espousing of an Ideology: A set of ideas that best serve to explain political and social phenomena and thus attempting a correlation between the theory used in explanation with that of the "goings on" observed. For long periods in history Philosophers and Social Scientists have debated whether Liberalism, Marxism, Anarchism, Structuralism or Methodological Individualism best serve as theoretical explanations of social reality.
In this same instance we find Ideologists today who advocate Conspiracy Theory. Like so many others in the realm of theoretical and philosophical explanation they too employ ideal frameworks that account for observed phenomena. Regardless of the aspects that encompass specific conspiracy theories, whether they are single point conspiracy theories like 911 or Meta conspiracy theories of the New World Order, they all occupy the spectrum of political ideology. This is because they advocate an explanation for observed phenomena. As where Marxism does it through the lens of capitalism and its dialectic with the human essence, Liberalism through inalienable individual property rights, conspiracy theorists do it through the lens of an esoteric operating cabal - for instance a horde of business and political agents responsible for 911 and its cover up.
All these ideologies execute the same cognitive apparatus when examining social data. They have a target point to explain and go out about it by utilizing their philosophical and ideological perspective and beliefs to explain the phenomena at hand and simultaneously reinforce their belief system in a circularity manner. Once can examine 911 from various stand points including the official explanation stated by the U.S Government or from the perspective of both Meta conspiracy and single point conspiracy theory. It is worth noting that often proposed theories have to take into account competing theories, and thus in effect explain them too. Here conspiracy theorists would argue that the Ideologies of both Liberalism and Democratic Government are facilitated by the ruling elite to distract us from the real "goings on" at hand.
One of the most significant indicators of Conspiracy Theory as Ideology is its remedy for the perceived problem; the way out of the turmoil and into a utopian future akin to the Marxist proposal for the future design of society and mankind. Ironically it is here where Conspiracy Theory shares its most identifiable resonance with the established philosophies of Liberalism and Marxism.
Certain conspiracy theorists such as Alex Jones cry out for the Republicanism of the founding fathers of the American constitution - intended to safeguard the individual rights of citizens from ever intrusive Government legislation. This is an obvious parallel with Liberalism and Anarchism yet not attributed as one due to the predisposed schema that Liberalism is a conspiratorial design. Then we have the utopian future of a collective society void of greed and ego to better mankind and society against the tide of corporatism and the concentration of power in Government as advocated by David Icke. This is an obvious appeal, whether subconscious or not, to Anarcho-Communism.
Yet it is these political and social aspirations of Conspiracy Theory that presents it in the light of ideology: the analyzing of socio-political phenomena with theories of causations and justification as well as proposals for future change. Conspiracy Theory is also the political ideology of the disengaged and of the fringe. As previous Socialist, Feminist and Civil Rights movements were motivated by the disenfranchised in society at the time, we now have conspiracy theorists disillusioned with globalization, Sovereign centralization and free market economics to the point where they can no longer follow or assert the dominant paradigms of the modern world, especially when associated with the official accounts of 911. They therefore find solace in a theory that explains the current state of affairs to them in a more appealing manner with the possibility of change - the same as any other political ideology.