So your becoming a Christian was involuntary, therefore no problem with private judgment. Like some are born Muslim, so that must be right too. Got it. Too bad for atheists and others with no such background. They can't go crossing that Tiber (or go visit Mecca etc) unless they figure out, from private judgment, it's the right thing to do. And that's a problem, because "private judgment" is, after all, fallible. We or they could be wrong, no matter what we decide.
But of course I reject your premise. There is no scriptural account of anyone becoming a Christian by birth, or by infant baptism. Your volition made you Catholic, and therefore, regardless of the degree to which it is obscured, your private judgment, your decision to seek fellowship with any given community of faith, was and remains based on your fallible private judgment.
we take the scripture on its direct face value
Except for here:
Jesus the Door is obviously an allegory
Obviously? Obvious to whom? To you, in the great wisdom of your private judgment? Well it IS obvious, and requires no magisterium for such a conclusion, but it is obvious because God gives some light to every man, including the ordinary powers of language, reason, and reasonable inferences.
By which we also conclude that Jesus really meant what he said when he said "the flesh profits nothing; my words are spirit, and they are life."
Do you see the problem here? And I testify to this because I have engaged many a cultist, all of whom had their preprogrammed library of excuses for not accepting "face value" teachings of Scripture. There is nothing about transubstantiation that has anything to do with the face value of Scripture.
Transubstantiation per se was neither seen nor heard of until invented by Benedictine monk Radbertus in the 9th Century. It was ratified in general terms in 1215 by the 4th Lateran Council, and came through the instrumentality of pagan Greek philosopher Aristotle at the hand of Aquinas in the 13th Century. It explains nothing. It only obscures.
As for Ignatius, surely you understand his frame of reference. In the battle against Docetism, it was necessary to point out that the basis of the Eucharist was not some phantom aeon of the Christ spirit, but God come in the flesh. His words correspond exactly to the afore-quoted Tertullian, who inferred from the figure of the Eucharist a real, corporeal Christ whom the Gnostics could not deny.
But neither in Tertullian nor Ignatius are we locked into the special meaning of “is” created out of whole cloth by Radbertus and sealed into Roman doctrine by Aquinas. To shove the entire package known as transubstantiation into the verb of being wherever you find it is to ignore, to amputate, if you will, a necessary understanding of the ordinary language of the day, an understanding you yourself have just now acknowledged, in that you have no problem taking “is” non-literally when you do not have a Roman doctrine at stake:
Jesus the Door is obviously an allegory
So you see perhaps the problem of the Protestant apologist. To us, it appears your RC hermeneutic grants you wide latitude to use “is” however it suits you at the moment. You can then claim you are the only ones who take it at face value (because you have also defined “face value”), when in fact that is the opposite of what has just happened.
The Protestant hermeneutic, on the other hand, does not allow extraordinary meanings to words that work just as well with ordinary meanings. This does limit us; it compels us to exclude hidden meanings not evident from the ordinary meanings of words. Especially words that had no definition until eight centuries later.
As for your commentary on Augustine, I am familiar with the “both/and” theory of reconciling his apparently Protestant language regarding signs with the much later development of transubstantiation. If you find that theory credible or satisfactory, that’s up to you. For me, I am again bound to ordinary meanings for ordinary language. It is obvious he does not see the sign as also being the thing signified:
“Now, as to follow the letter, and to take signs for the things that are signified by them, is a mark of weakness and bondage”
Augustine has gone to great pains to ensure his reader does NOT do the very thing you invite him to do. He clearly separates the thing the sign is about from the sign itself, and he further blockades abuse of his words by calling such confusion as you advocate a weakness.
Baptized people do not physically die and then rise from the dead in the baptismal waters. If that were the case, there would be none who doubt the truth of the Christian faith. But it is instead a spiritual exercise, with an outward sign to an inward reality.
Likewise, the bread and the wine of the holy meal are signs by which we remember and adore the one who died for our sins. It breaks my heart that He had to go to such lengths for someone as unworthy as me. But He did, and I am grateful for it.
How anyone can suggest we do not think of His sacrifice for us as real, and His presence with us as exquisitely real, is beyond me. God is spirit, and nothing is more real than God. His words are spirit, and they are life.
Birth has nothing to do with it. We become Christians when God makes us Christians. That, ordinarily is baptism. The soul and its volition has nothing to do with the soul getting the mark of the Holy Spirit. There is no direct scripture on infant baptism, because all interesting and instructive conversions are of adults. Indirectly, we read on a number of occasions that people were baptized "and their house", or maybe "household" ("οικος"). That is likely to include children. Christ asked the children to be brought to Him; why wouldn't He want them to brought to Him in the most meaningful sense of the word?
On this "private judgment" issue I have a feeling you have a question that I am not getting, or maybe there is something in it that is important to you that I never felt important. Like anything else I do there is grace of God in it and also my own private reason cooperating with grace. That is about all.
Obviously?
Just obvious: one allegory (door) is followed by another (vine), no sacrament is established based on doors, no insistence on the meaning of "door" being literate and no misunderstanding. The face value of allegory is allegory; no one is denying that they are plentiful. The point remains that John 6 is not framed as allegory, is in context of the feeding of thousands and the manna from heaven, and the impending sacrifice of Christ to give us life, -- neither three are allegorical. It is in the context of real physical events.
Jesus really meant what he said when he said "the flesh profits nothing; my words are spirit, and they are life."
Correct, neither this is allegorical speech, but it does not negate the physical character of the Eucharist. It furthers the explanation by noting that the effect of the Eucharist (the "profit" from it) is purely spiritual. It does not say that the Eucharist itself is purely spiritual. Christ did not change His mind from one verse to the next.
There is nothing about transubstantiation that has anything to do with the face value of Scripture
Correct again, the face value is simply "this is my body, eat it, and do it". How the bread becomes a body is not explained, nor should it be explained. The word of Christ, spoken solemnly at the Last Supper and the discussion in the future tense in John 6 with strikingly insisting, black-and-white tone should be enough whether we can explain it through some scholastic trick or not.
neither in Tertullian nor Ignatius are we locked into the special meaning of “is”
Sure we are, in the plain old meaning of "is" being "is". The Eucharist is Christ's body; who does not believe that Christians should stay away from. Note that he did not say "whoever thinks Christ is a spirit" are heretics, but "whoever does not believe the Eucharist is the body of Christ is a heretic". The Docetist context changes nothing.
The Protestant hermeneutic, on the other hand, does not allow extraordinary meanings to words that work just as well with ordinary meanings.
Well, that is unfortunate because there was nothing ordinary about virgin birth, death and resurrection of Christ, nor, to that matter, "manna" falling from the sky and five loaves feeding thousands. Of course the word "is" can be used to build an allegory as well as build a direct message; but the fact that Jesus speaks contrary to people's intuition, insists on what seems to them an absurdity being truth; and that the accounts at the Last Supper and in 1 Cor. 11 support the literal meaning but not an allegorical meaning, -- all that shows that the approach to avoid extraordinary meaning when talking of extraordinary things is not only stupid philosophically but also fails the plain text in front of you.
If you find that theory [transubstantiation] credible or satisfactory
Not particularly; on that I am with the Orthodox, I don't think a miracle of the Real Presence can or needs to be explained. The Eucharist is Christ's body not because Aquinas cleverly consulted Aristotle, but because Jesus said so.
He clearly separates the thing the sign is about from the sign itself
Good, if you deal with a sign. We don't, in this case: Christ did not say "this is a sign of my body; eat the sign", He said "this is my body for you to eat".
Baptized people do not physically die and then rise from the dead in the baptismal waters
That would be because Christ did not die and rise in baptism and did not ask us to do baptism in order to bring us to the Sacrifice of the Cross. The teaching on the Eucharist has no analogy in other sacraments of the Church