The term ideology has a wide range of meanings. Patrick Corbett used the one term 'ideology' for such moral, political, and religious beliefs as Gandhism, Catholicism, Leninism, Marxism, and American Democracy. But he insists that to be considered an ideology for his purposes a system of thought must "have important implications for a wide range of conduct." (Patrick Corbett, Ideologies, 1965, p.12.) Louis Halle used the word ideology for systems of thought which are "implicitly totalitarian" and which therefore "require suppression of whatever does not conform" [Louis Halle, The Ideological Imagination, 1972, p.6].
Generally, but without wanting to be too precise at the margin, I prefer the term 'ideology' to describe a commitment to a political summum bonum or ultimate goal. We can then call any other commitment to a way of life, whether or not there is a belief in God, a religion. In our terminology some religions such as Zen Buddhism are atheistic, and ideologies such as Nazism and Marxism have a very strong faith and commitment. In some cases a religion such as Confucianism or Islam can become an ideology if it becomes a political system for organizing a nation. But nothing hangs on the distinction for our analysis in chapter 2 and classification in chapter 3.
Although in every religion and ideology new metaphors can be adopted from other uses of language, the basic structure of the logical system in which they are organized is likely to remain fairly constant. If the basic structure is altered believers will sense a change in how they are asked to perceive reality and how they should order their lives in the light of the goal they have in mind. Either they will adopt the new model of religion or ideology with enthusiasm, in which case a conversion has occurred, or they will stubbornly retain the old metaphors. In eastern Europe for example the communist ideologists eventually discovered that no amount of indoctrination in the Marxist model had changed the basic religious attitudes of the people.