To be clear: an ideology is a belief system with an inadequate basis in reality; a religion is a belief system with no basis in reality whatever.

...we no longer have intellectually satisfying arrangements in our educational system, in our arts, humanities or anything else; instead we have slogans and ideologies. An ideology is a religious or emotional expression; it is not an intellectual expression.

. . ideology. . . is an instrument of power; a defense mechanism against information; a pretext for eluding moral constraints in doing or approving evil with a clean conscience; and finally, a way of banning the criterion of experience, that is, of completely eliminating or indefinitely postponing the pragmatic criteria of success and failure. — Jean-François Revel1

Ideology consist of a specific objective level, of a relatively coherent ensemble of representations, values and beliefs: just as 'men', the agents within a formation, participate in an economic and political activity, they also participate in religious, moral, aesthetic and philosophical activities. Ideology concerns the world in which men live, their relations to nature, to society, to other men and to their own activity including their own economic and political activity. The status of the ideological derives from the fact that it reflects the manner in which the agents of a formation, the bearers of its structures, live their conditions of existence; i.e. it reflects their relation to these conditions as it is 'lived' by them. Ideology is present to such an extent in all the agents' activities that it becomes indistinguishable from their lived experience. To this extent ideologies fix in a relatively coherent universe not only a real but also and imaginary relation: i.e. men's real relation to their conditions of existence in the form of an imaginary relation. This means that in the last analysis ideologies are related to human experience without being thereby reduced to a problematic of the subject—consciousness. This social-imaginary relation, which performs a real practical—social function, cannot be reduced to the problematic of alienation and false consciousness.

Ideology is a specious way of relating to the world. It offers human beings the illusion of an identity, of dignity, and of morality while making it easier for them to part with them.

Ideology is a system of beliefs, held in common by the members of a collectivity.

Here’s a simple definition of ideology: “A set of beliefs about the proper order of society and how it can be achieved.”8 And here’s the most basic of all ideological questions: Preserve the present order, or change it? At the French Assembly of 1789, the delegates who favored preservation sat on the right side of the chamber, while those who favored change sat on the left. The terms right and left have stood for conservatism and liberalism ever since. Political theorists since Marx had long assumed that people chose ideologies to further their self-interest. The rich and powerful want to preserve and conserve; the peasants and workers want to change things (or at least they would if their consciousness could be raised and they could see their self-interest properly, said the Marxists). But even though social class may once have been a good predictor of ideology, that link has been largely broken in modern times, when the rich go both ways (industrialists mostly right, tech billionaires mostly left) and so do the poor (rural poor mostly right, urban poor mostly left). And when political scientists looked into it, they found that self-interest does a remarkably poor job of predicting political attitudes.9 So for most of the late twentieth century, political scientists embraced blank-slate theories in which people soaked up the ideology of their parents or the TV programs they watched.10 Some political scientists even said that most people were so confused about political issues that they had no real ideology at all.11 But then came the studies of twins. In the 1980s, when scientists began analyzing large databases that allowed them to compare identical twins (who share all of their genes, plus, usually, their prenatal and childhood environments) to same-sex fraternal twins (who share half of their genes, plus their prenatal and childhood environments), they found that the identical twins were more similar on just about everything.12 And what’s more, identical twins r

The contemporary era constantly proclaims itself as post-ideological, but this denial of ideology only provides the ultimate proof that we are more than ever embedded in ideology. Ideology is always a field of struggle - among other things, the struggle for appropriating past traditions.

When the Berlin Wall was dismantled I, like many other naive observers, supposed that the age of ideology was at an end. On the contrary, ideology proliferated, blossomed and balkanised; we underestimated people’s need, quasi-religious in nature, for an all-encompassing cause.

Unlike science, an ideology is constructed of conventional ambiguous expressions, which require interpretation. It is impossible to verify or experimentally confirm an ideological statement, one cannot refute these for they are meaningless. […] While arising, an ideology may have pretensions to be scientific. But having become an ideology, it loses all the major characteristics of science.

Ideologies have become more powerful than humanity's real experience, faith, and the different values we live by. Some will misunderstand unity as uniformity: ‘You must be like us.’ No, it cannot be so. Nor can diversity be understood as a way of living without criteria or order. The latter lose sight of the fact that since the very creation of the world, the gift of nature, the gift of human life, the gift of so many different things that we experience and celebrate, cannot be sustained by inventing my own rules and doing things my way. These are ideological positions. When an ideology becomes, so to speak, the master of my life, then I can no longer dialogue with another person because I have already decided how things will be. Therefore, I am closed to encounter and transformation cannot take place. And this can happen anywhere in the world, on any subject. This obviously makes it very difficult to be Church, to be community, to be brothers and sisters.

The particular conception of "ideology" makes its analysis of ideas on a purely psychological level. If it is claimed for instance that an adversary is lying, or that he is concealing or distorting a given factual situation, it is still nevertheless assumed that both parties share common criteria of validity — it is still assumed that it is possible to refute lies and eradicate sources or error by referring to accepted criteria of objective validity common to both parties. The suspicion that one's opponent is the victim of an ideology does not go so far as to exclude him from discussion on the basis of a common theoretical frame of reference. The case is different with the total conception of ideology. When we attribute to one historical epoch one intellectual world and to ourselves another one, or if a certain historically determined social stratum thinks in categories other than our own, we refer not to the isolated cases of thought-content, but to fundamentally divergent thought-systems and to widely differing modes of experience and interpretation.

One handy distinction is to think of coalitions being built around issues, and ideology being a worldview. An ideology is a set of ideas that explains what makes society tick and what its values are. You don’t have to agree on that with other people in order to fight for health care, housing, affirmative action, or whatever. You do have to agree with somebody’s ideology, I think, if you’re going to join certain kinds of organizations that demand ideological unity, from the Boy Scouts to the Communist Party. But coalitions, networks, and alliances should never make the mistake of demanding ideological unity. They can expect unity around an issue.

Ideological' is a social reality whose very existence implies the non-knowledge of its participants as to its essence - that is, social effectivity, the very reproduction of which implies that the individuals 'do not know what they are doing.