believer

noun

1. A person who believes; especially regarding religion.

   “She's a believer in life after death.”

   “But the other two were, comparatively speaking, clean shaved, which of course gave the enemy a larger extent of open country to operate on, though in Mahomed's case the mosquitoes, recognising the taste of a true believer, would not touch him at any price.”

   “A long list of thinkers, both believers and nonbelievers, have posited something like an innate religious instinct.”