true believers

Noun

true believer (plural true believers)

1. A strict follower of a doctrine.
   • When he had repoſed four years and four months in the boſom of care, rocked in the cradle of proſperity, he was brought forth, according to the cuſtom of true believers, and committed to the charge of moralifts of high fame, poliſhers of noble manners, and ſearchers of true knowledge, that they...1769, Firishta, translated by Alexander Dow, Tales translated from the Persian of Inatulla of Delhi, volume I, Dublin: P. and W. Wilson et al., page 4
2. An individual who maintains unwavering belief in a claim irrespective of empirical evidence, including clear or conclusive proof of its falsity or fabrication.
3. Used other than figuratively or idiomatically: see true, believer.