You are misusing Augustine’s figurative writings to support the doctrine of transubstantiation. The following example is a case in point:
That bread, which you can see on the altar, sanctified by the word of God, is the body of Christ. That cup, or rather what the cup contains, sanctified by the word of God, is the blood of Christ. It was by means of these things that the Lord Christ wished to present us with his body and blood, which he shed for our sake for the forgiveness of sins. If you receive them well, you are yourselves what you receive. You see, the apostle says, We, being many, are one loaf, one body (1 Cor. 10.17). That’s how he explained the sacrament of the Lord’s Table; one loaf, one body, is what we all are, many though we be (Augustine, Sermons, 227).
Augustine believed that in a sense the elements are the body and blood of Jesus. “The bread…is the body of Christ…that cup…is the blood of Christ.” In what sense is he speaking? Is the substance of the bread changed into the body of Christ? Or is bread the body of Christ in a symbolic sense? We can readily discover the answer to this all important question.
First, looking at the context, it is clear that Augustine is using figurative language. Just as he asserts that the bread is the body of Christ, he is equally emphatic that Christians are one loaf, one body. Clearly, he means that the one Eucharistic loaf represents the unity among believers. Similarly, “by means of these things” - the bread and the cup - the Lord presents his people with his body and blood. The Eucharistic elements are the figure or sign of Christ, as Augustine asserts explicitly elsewhere in his writings:
- The Lord did not hesitate to say: “This is My Body”, when He wanted to give a sign of His body” (Augustine, Against Adimant).
- He [Christ] committed and delivered to His disciples the figure of His Body and Blood” (Augustine, on Psalm 3).
- [The sacraments] bear the names of the realities which they resemble. As, therefore, in a certain manner the sacrament of Christ’s body is Christ’s body, and the sacrament of Christ’s blood is Christ’s blood” (Augustine, Letter 98, From Augustine to Boniface).
- The Eucharist is the figure of the body and blood of Jesus. Since the bread and wine represent the body and blood of Christ, it is acceptable to call them His body and His blood. The bread resembles the body; therefore it is called the body even though it is not the reality it represents. That is perfectly normal in figurative language.
Augustine believed that the bread and cup were signs, which he defines in this manner: “a sign is a thing which, over and above the impression it makes on the senses, causes something else to come into the mind as a consequence of itself” (On Christian Doctrine, 2, 1). Therefore, when we see the bread, something else comes to mind, namely, the body of Christ. The mistake of the modern Catholic Church is to confuse the sign with the reality it represents.
“Now, as to follow the letter, and to take signs (such as the sacrament of the body and blood of the Lord) for the things that are signified by them, is a mark of weakness and bondage; so to interpret signs wrongly is the result of being misled by error" (Augustine, On Christian Doctrine 3,9). To confuse the bread (the sign) for the body of Christ (the signified) is, according to Augustine, weakness, bondage and error.