skepticism vs incredulity

skepticism and incredulity both are nouns.

Word	Noun	Adjective	Verb	Adverb
skepticism	Yes	No	No	No
incredulity	Yes	No	No	No

As nouns, skepticism and incredulity are synonyms defined as:

Other synonyms of skepticism include disbelief, mental rejection, scepticism.

skepticism (noun)	incredulity (noun)
doubt about the truth of something	doubt about the truth of something
the disbelief in any claims of ultimate knowledge