Heidegger's Bible Handbook: NT Apocrypha: Identifying the Apocryphal
20. All these and other Apocryphal New Testament Books the Holy Fathers of old distinguished from the true Canonical New Testament Books by three notes and marks.
And these are the principal Apocryphal Books of the New Testament, never authentically handed down and commended to the Christian Church, never received by it, and betraying themselves by internal indications and marks, that they are by no means θεόπνευστοι/inspired. And, so that the doubtful Books might be able more easily to be discerned and distinguished from the certain, the human from the Divine, the Apocryphal from the Canonical, three notes, as κριτήρια/criteria or a standard of judgment, were prescribed by the Holy Fathers, especially Epiphanius in his libro de hæresibus, and Saint Augustine in his libris contra Faustum. First, that nothing is able to be proven concerning the trustworthiness and authority of the Apocryphal Books from the testimonies of the most ancient Fathers. Second, that their style does not at all agree with the style of the Sacred Books. Third, and finally, that in sense and doctrine they differ from the truly holy and Divine Books.
 Faustus of Mileve (fourth century) was a celebrated Manichæan teacher. While a Manichæan, Augustine, wrestling with questions, sought an audience with him. Finding Faustus unable to answer his questions, Augustine rejected Manichæism as a collection of unsubstantiated fables.