radicalism vs sectarianism

radicalism

noun
  • Any of various radical social or political movements that aim at fundamental change in the structure of society 

sectarianism

noun
  • Rigid adherence to a particular sect, denomination, ideology, or party. 

  • A political system in which power is shared among religious sects based on a constitutional formula distributing public offices among these sects 

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