diatribe vs polemicist

diatribe

noun
  • A speech or writing which bitterly denounces something. 

  • An abusive, bitter, verbal attack or criticism: denunciation. 

  • A prolonged discourse. 

polemicist

noun
  • A person who puts forward controversial views 

  • A person who writes polemics 

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