backslide vs get worse

backslide

verb
  • To revert back into a life of sin after being saved. 

  • To regress; to slip backwards or revert to a previous, worse state. 

  • To shirk responsibility; to renege on one's obligations or commitments. 

noun
  • A backward regression; a reverting back to a worse state. 

  • A dance move in which the feet are alternately slid back and the heels lifted, giving the illusion of walking forwards while actually moving backwards. 

get worse

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