atheism vs nontheism

atheism

noun
  • Absence of belief in a particular deity, pantheon, or religious doctrine (notwithstanding belief in other deities). 

  • Absence of belief that any deities exist (including absence of the concept of deities). 

  • Rejection of belief that any deities exist (with or without a belief that no deities exist). 

  • Belief that no deities exist (sometimes including rejection of other religious beliefs). 

nontheism

noun
  • Any of a range of concepts regarding spirituality and religion which do not include the idea of a deity in the form of a theistic god or gods. 

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