Noun

(-)

Unwillingness or inability to believe; doubt about the truth or verisimilitude of something; disbelief.

* 1916 , Edgar Rice Burroughs, Tarzan and the Jewels of Opar , ch. 24:

Wide went her eyes in wonder and incredulity , as she beheld this seeming apparition risen from the dead.

* {{quote-book, year=1963, author=(Margery Allingham), title=(The China Governess)

, chapter=8 citation , passage=It was a casual sneer, obviously one of a long line. There was hatred behind it, but of a quiet, chronic type, nothing new or unduly virulent, and he was taken aback by the flicker of amazed incredulity that passed over the younger man's ravaged face.}}

(rare) Religious disbelief, lack of faith.