disbelief vs unbelief

disbelief

noun
  • The loss or abandonment of a belief; cessation of belief. 

  • Astonishment. 

  • Unpreparedness, unwillingness, or inability to believe that something is the case. 

unbelief

noun
  • An absence (or rejection) of belief, especially religious belief 

How often have the words disbelief and unbelief occurred in a corpus of books? (source: Google Ngram Viewer )