The definition of incredulity is the state of not believing.
An example of incredulity is the mindset of an atheist.
unwillingness or inability to believe; doubt; skepticism
Origin of incredulityMiddle English incredulite from Old French incrédulité from Classical Latin incredulitas: see in- and credulity
The state or quality of being incredulous; disbelief.
Attested since 1430. From Old French incredulité, from Latin incredulitas, from incredulus (“unbelieving”) + -itas (“-ity”)