saving grace vs state of grace

saving grace

noun
  • God's grace or blessing, enabling sinners to attain salvation. 

  • A redeeming quality or factor. 

state of grace

noun
  • A condition free from mortal sin, in which one has the favor of God and enjoys unmerited divine assistance. 

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