purgation vs purification

purgation

noun
  • The process or act of purging, such as by the use of a purgative. 

  • The process or act of cleansing from sin or guilt. 

purification

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

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

  • 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 purgation and purification occurred in a corpus of books? (source: Google Ngram Viewer )