“it is a terribly demanding criterion that we must always apply first to ourselves by asking: do we live and embody, through our deeds, everything that God teaches and demands of us?”
Either this is a poor summarization of what Augustine said, or he has nothing to say. Without mentioning the empowerment of the indwelling Holy Spirit , and being yielded to filling with the Holy Spirit by clinging desperately to HIS revelation in only the Bible, this putative “practical “ application is totally impractical. Hebrews 11:6: “But without faith it is impossible to please Him: for he that cometh to God must believe that He is, and that He is a rewarder of them that diligently seek Him.”
St. Augustine was not one those "sola scriptura" zealots.