free grace vs thanksgiving

free grace

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

thanksgiving

noun
  • A short prayer said at meals; grace, a benediction. 

  • An expression of gratitude. 

  • A public celebration in acknowledgement of divine favour. 

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