infidel vs non-believer

infidel

adj
  • Rejecting a specific religion. 

  • Of, characteristic of, or relating to unbelievers or unbelief. 

noun
  • One who does not believe in a certain religion. 

  • One with no religious beliefs. 

  • One who does not believe in a certain principle. 

non-believer

How often have the words infidel and non-believer occurred in a corpus of books? (source: Google Ngram Viewer )