Not converted (especially in the religious sense)(adjective)
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Use "unconverted" in a sentence
"Categorized as "long-term unconverted prisoners," they refused to pledge loyalty to Seoul -- as have 20 fellow spies who still remain behind bars."
"Are you preaching to the "unconverted"-- that is, are you bringing in the previously disengaged or the merely aware to a social movement to strengthen its numbers and potential?"
"The converted are accused of hating themselves, and the unconverted are accused of hating everybody else."