On the Christian Faith

His five books De fide ad Gratianum were written between 378 and 380 in response to several requests by the Emperor Gratian. In the work Ambrose argues against a series of Arian propositions (De fide 1.34–40) and answers objections to his own views that came from the homoion party.

David G. Hunter, “Fourth-Century Latin Writers: Hilary, Victorinus, Ambrosiaster, Ambrose,” in The Cambridge History of Early Christian Literature, ed. Frances Young, Lewis Ayres, and Andrew Louth (Cambridge: Cambridge University Press, 2004), 311.