Ideology is not a collection of beliefs and opinions. Ideology is a system of beliefs and opinions. The parts (beliefs and opinions) are interconnected and form a complex whole. The whole is organized according to some core principles or themes.  The sine qua non of ideological discourse is the “ideological square”, an elaboration of Us versus Them thinking:

  1. Exaggerate Our Good Things: Our vision is good and true.
  2. Exaggerate Their Bad Things: Their vision is evil and false.
  3. Minimize Our Bad Things: Our vision has no serious downside.
  4. Minimize Their Good Things: Their vision has no merit.

Political coalitions are more or less ideological.  On the less ideological side, they may be held together by alliances of convenience, whose common cause may be more dislike of the other side than broad agreement on a range of issues. Or their members may share a key sentiment, like ‘keep government small’ but for different reasons, e.g., pro-business, anti-bureaucracy, pragmatism, efficiency, separation of church and state, distrust of do-gooders, freedom from coercion or interference, etc. As allies in a cause, they may become sympathetic to other points of view within their coalition, but that is different than embracing an ideology.

Ideologies are like secular religions – the essence of religion not being belief in supernatural entities or alternative worlds like heaven, but a “...system of symbols which acts to establish powerful, pervasive, and long-lasting moods and motivations in men by formulating conceptions of a general order of existence and clothing these conceptions with such an aura of factuality that the moods and motivations seem uniquely realistic." (Geertz 1993)

Within every political party, there are factions that are more ideological than others. That is, they have developed a system of ideas about the general order, ideas held with such confidence and fervor that they are clothed with an aura of factuality.

The problem with systems is their vulnerability to disintegration. With systems, everything’s connected: break a few links and the whole thing comes tumbling down. This vulnerability fosters a sense of threat. Hence, ideologues are often paranoid. Conspiracies and enemies abound. You get Us and Them and the Ideological Square.

References:

Geertz, C. (1993) Religion as a cultural system. The interpretation of cultures: selected essays, Geertz, Clifford, pp.87-125. Fontana Press.

Van Dijk, Teun A. (2005) Politics, ideology and discourse. Elsevier Encyclopedia of Language and Linguistics. Volume on Politics and Language (Ruth Wodak, Ed.), pp. 728-740.