preach vs spread the gospel

preach

verb
  • To proclaim by public discourse; to utter in a sermon or a formal religious harangue. 

  • To give a sermon. 

  • To advise or recommend earnestly. 

  • To teach or instruct by preaching; to inform by preaching. 

  • To give advice in an offensive or obtrusive manner. 

spread the gospel

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