Fundamentalist Christianity , is a movement that arose mainly within British and American Protestantism in the late 19th and early 20th centuries in reaction to modernism and certain liberal Protestant groups that denied doctrines considered fundamental to Christianity yet still called themselves `` Christian '' . Fundamentalist Christianity , is a movement that arose mainly within British and American Protestantism in the late 19th century and early 20th century in reaction to modernism and certain liberal Protestant groups that denied doctrines considered fundamental to Christianity yet still called themselves `` Christian . ''