One who disbelieves, one who does not believe.(noun)
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Use "disbeliever" in a sentence
"He is a disbeliever, which is just as bad as being a believer."
"It must be noted that he had had fairly extensive experience of spiritualism; he had made regular experiments with Mrs. Haydon at his brother George's house (the paper on which these are recorded is undated, but it must have been before 1863); he was referred to as a disbeliever in an article in the "Pall Mall Gazette" during January"
"Instead, the man seeking to rescue the children and his fellow citizens from inhumane conditions has been called a disbeliever on national TV."