The Collaborative International Dictionary
Unbelievingness
Unbelieving \Un`be*liev"ing\, a.
Not believing; incredulous; doubting; distrusting; skeptical.
Believing the thing alleged no to be true; disbelieving; especially, believing that Bible is not a divine revelation, or that Christ was not a divine or a supernatural person. ``Unbelieving Jews.''
--Acts xiv. 2. [1913 Webster] -- Un`be*liev"ing*ly, adv. -- -- Un`be*liev"ing*ness, n.
Wiktionary
unbelievingness
n. Lack of belief; unbelief.