belief vs unbelief

belief

noun
  • Mental acceptance of a claim as true. 

  • Religious faith. 

  • One's religious or moral convictions. 

  • The quality or state of believing. 

  • Faith or trust in the reality of something; often based upon one's own reasoning, trust in a claim, desire of actuality, and/or evidence considered. 

  • Something believed. 

unbelief

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

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