If Augustine had no problem saying that the Eucharist is the body of Christ, yet say in the same sermon that it only signifies the body of Christ, I don’t think anyone else would either.
But nowhere does Augustine state that the Eucharist only signifies the Body of Christ. You are inserting this in like manner as Luther inserted "alone" in the passage that "we are saved by faith." Nothing that Augustine states contradicts his assertion that "That bread which you see on the altar, having been sanctified by the word of God, is the blood of Christ."
The only thing ambiguous about them, and of the assertions by that Pope and other Bishop on the “substance” of the bread and wine remaining the same, exists in your own mind since you will not explain them.
As to Pope Gelasius and Theodoret, not having the full documents from which your quotes were derived I must comment only on what you have posted. You would be wrong to attribute the precise late medieval scholastic meaning of "substance" to these writers of the 4th and 5th centuries. This is clearly seen in the quote from Theodoret which you give. Using the term "substance" he refers to the figure and form of the Eucharist, what in scholastic terminology would be referred to as their "accidents." He expressly states that the bread and wine do change:
But they are regarded as what they are become, and believed so to be, and are worshipped as being what they are believed to be.Notice that he states that they are to be worshipped, something which would be denied if they were only bread and wine. Again when speaking of the substance of our Lord's resurrected Body he states that this is its "form, figure, and limitation." Again, these are what the scholastics would call its accidents, not substance.
In his letter to the Romans St. Ignatius states that his desire for the bread of life is for the flesh of Jesus Christ, not for his death or sacrifice. This is what he would have received in Communion during the celebration of the Mass, just as stated by St. Justin Martyr. Nor would his inability to actually receive Communion take away his desire. Those imprisoned desire freedom even though they cannot achieve it.
Given that the major concern of Ignatius in his letter to the Smyraeans is the denial that our Lord possessed a body or suffered, nevertheless he does point out their rejection of the Christian understanding of the Eucharist:
[T]hey do not confess that the Eucharist is the Flesh of our Savior Jesus Christ.You mischaracterize the meaning of your first quote from St. Irenaeus. The Greeks mistook the Christians' sacramental Body and Blood for carnal flesh and blood. But this misunderstanding could only have happened because the Christians spoke of the Eucharist as the real Body and Blood of Jesus.
As for your second quotation, the Eucharist does indeed have two realities, a divine substance and earthly accidents.
Your quote from St. Athanasius takes nothing away from his statement that "after the great and wonderful prayers have been completed, then the bread is become the Body, and the wine the Blood, of our Lord Jesus Christ."
St. Cyril's use of the term "figure" refers to what the scholastics would call the accidents of the sacrament. Again notice how he insists:
[T]he invocation having been made, the bread becomes the Body of Christ and the wine the Blood of Christ.And:
He Himself, therefore, having declared and said of the Bread, "This is My Body," who will dare any longer to doubt? And when He Himself has affirmed and said, "This is My Blood," who can ever hesitate and say it is not His Blood?Can there be a stronger statement that the bread and wine changes and becomes the Body and Blood of Jesus Christ?
“But nowhere does Augustine state that the Eucharist only signifies the Body of Christ.”
Actually, that’s exactly what he does. See my previous post to Mrs. Don.O, as well as review the quotes already given. It’s pointless to go on if you won’t even attempt to address them.
“In his letter to the Romans St. Ignatius states that his desire for the bread of life is for the flesh of Jesus Christ, not for his death or sacrifice. This is what he would have received in Communion during the celebration of the Mass,”
Which would not be possible, since he was on his way to be martyred. It’s doubtful that Ignatius would have the same mechanical view as the RCC does on the Eucharist. He also speaks of loving Christ with the word “eros,” all designed to explain his desire to have Christ completely (though not in the sexual sense, as the word sometimes implies). It’s a shame to reinterpret Ignatius in such a way that his desire to have Christ is reduced to merely a desire to have communion, rather than his desire to give his all for Christ as a martyr.
“You would be wrong to attribute the precise late medieval scholastic meaning of “substance” to these writers of the 4th and 5th centuries....As for your second quotation, the Eucharist does indeed have two realities, a divine substance and earthly accidents.”
In theory, the RCC has always believed in transubstantiation. Therefore, if Augustine is a symbolist, and if Gelasius or Irenaeus believe in consubstantiation, (two substances) when the RCC only allows the “form” to be the same, but not the substance, and no sense of symbolism here, I think we can safely assume that there was no monolithic tradition passed down to the Apostles on the matter. Just men developing their theological ideas, some disagreeing, some agreeing, slowly, over a thousand years. In fact, not even Trent even actually defined what they meant by “sacrifice” in the first place, probably because of the scripture in Hebrews which declares that Christ already made a sacrifice, once and for all.
“Your quote from St. Athanasius takes nothing away from his statement that “after the great and wonderful prayers have been completed, then the bread is become the Body, and the wine the Blood, of our Lord Jesus Christ.”
It takes everything away from it, because Athanasius denies the RCC interpretation of John 6, by which the RCC justifies making the command for the Lord’s supper to be done “to remember me” into “for everlasting life” instead. If Augustine and even Christ Himself can speak figuratively of the Lord’s supper, it’s only natural for believers to do the same.