believer

noun

Etymology: From Middle English bilevar, bileever, belever, equivalent to believe + -er.

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.”