free grace vs purification

free grace

noun
  • A concept of grace as a gift given freely by God, without regard to entitlement or merit. 

purification

noun
  • A religious act or rite in which a defiled person is made clean or free from sin. 

  • The act or process of purifying; the removal of impurities. 

  • The pouring of wine into the chalice to rinse it after communion, the wine being then drunk by the priest. 

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