the.com/fundamentalism

means A movement or mindset built on treating a fixed set of core beliefs as non-negotiable, literal, and immune to revision or compromise.

from Coined in early 20th-century America, directly from a series of pamphlets called 'The Fundamentals,' published around 1910 by conservative Protestants to defend what they saw as the essential, undeniable truths of Christianity against modernist and liberal theology. 'Fundamentalist' followed soon after as a label for those who held the line. The word stayed rooted in religion for decades before it broadened — now applied, often critically, to any ideology (political, religious, or otherwise) that treats its core tenets as beyond question.