Both religion and science often have been regarded as forms of ideology. This has created interesting problems for the scientific study of religion. This paper presents a new theory of "ideology" that is based on Dan Sperber's distinction between intuitive and reflective beliefs as well as on his idea of metarepresentation. In ideological thinking it is presumed that decoupling any given beliefs from a given metarepresentational context a priori leads to their misunderstanding. Only intuitive beliefs are free from ideology; they are based on direct perception or very simple inference. All reflective beliefs, scientific and religious alike, are potentially ideological. Ideology thus is contrasted with everyday common sense, not with science. The study of ideologies is not necessarily itself ideological in the same sense as its varying objects. "Ideology" is a graded category; beliefs and arguments are more or less ideological, not either ideological or non-ideological.