religious studies vs theology

religious studies

noun
  • The academic study of religious beliefs, behaviours and institutions. 

theology

noun
  • Synonym of religious studies 

  • Subjective marginal details. 

  • An organized method of interpreting spiritual works and beliefs into practical form. 

  • The study of God, a god, or gods; and of the truthfulness of religion in general. 

  • A particular belief within a religion. 

How often have the words religious studies and theology occurred in a corpus of books? (source: Google Ngram Viewer )