The Collaborative International Dictionary
Come-outer
Come-outer \Come-out"er\, n. One who comes out or withdraws from a religious or other organization; a radical reformer. [Colloq. U. S.]
Wiktionary
come-outer
n. 1 One who abandons or withdraws from an established religion, opinion, custom, creed, etc. 2 One who seeks radical political or religious reform.
Wikipedia
Come-outer
Come-outer is a phrase coined in the 1830s which denotes a person who withdraws from an established organization, or one who advocates political reform.