fervor vs insincerity

fervor

noun
  • Heat. 

  • An intense, heated emotion; passion, ardor. 

  • A passionate enthusiasm for some cause. 

insincerity

noun
  • Property of being insincere, lacking sincerity or truthfulness. 

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