OverviewReligious fundamentalism, or just "fundamentalism", refers to any kind of reactionary religious sect which focuses heavily on doctrine, often emphasizing violent retribution (immediate or delayed) for those who violate doctrine and promising post-mortem rewards for those who obey it in spite of personal moral objection or uncertainty.
The original usage of the term was in reference to Protestant fundamentalism, "a movement in North American Protestantism that arose in the early part of the 20th century in reaction to modernism" [W] and which emphasized that the Bible is literally true both as a moral guide and as a historical record.
 Other Uses
The word "fundamentalism" is sometimes used to indicate a relatively conservative position within a body of thought on any subject, not necessarily religious or philosophical in nature, e.g. "I'm a bit of a fundamentalist about quantum physics; the 'many worlds' interpretation just seems too far-fetched to me."