I know of no heresy condemnations primarily about the Real Presence until the eleventh century. Perhaps you can enlighten me.
Certainly people who were heretical on other grounds, like the Gnostics and in a more nuanced way the Nestorians, were accused of denying or having an incorrect understanding of the Real Presence.
But I don’t know of any Christians with an orthodox Christology/Trinitarian theology who were condemned for denying the Real Presence.
This is actually a potential argument for the Protestant position, since Ratramnus, for instance, was never condemned until Berengar drew on his work several centuries later, and various Fathers, most notably Augustine, said things that sound like a “Calvinist” theology of the Eucharist at times (though Augustine also said things about Eucharistic sacrifice and worshiping Christ in the Host that are radically different from Protestant Eucharistic theology).
But the idea of “secret believers” who held to proto-Protestant views underground is generally a fantasy invented by people who can’t support their views from early evidence.
I don’t know of anybody being accused of being a heretic because of their belief in the substance of the Eucharist until around 1000AD when the belief in transubstantiation was formalized. Before that many different beliefs were acceptable. Certainly starting with Cyril of Jerusalem and Ambrose in the 4th Century, there were those stating that the Eucharistic elements changed in substance. Augustine came after them and taught differently.
In Augustine’s
On Christian Doctrine Book III he clearly states:
“24. If the sentence is one of command, either forbidding a crime or vice, or enjoining an act of prudence or benevolence, it is not figurative. If, however, it seems to enjoin a crime or vice, or to forbid an act of prudence or benevolence, it is figurative. “Unless you eat the flesh of the Son of man,” says Christ, “and drink His blood, you have no life in you.”
John 6:53 This seems to enjoin a crime or a vice; it is therefore a figure, enjoining that we should have a share [communicandem] in the sufferings of our Lord, and that we should retain a sweet and profitable memory [in memoria] of the fact that His flesh was wounded and crucified for us.”
newadvent.org/fathers/12023.htm
I have seen quotes taken from Augustine to support his belief in transubstantiation such as:
“What you see is the bread and the chalice; that is what your own eyes report to you. But what your faith obliges you to accept is that
the bread is the body of Christ and the chalice is the blood of Christ. This has been said very briefly, which may perhaps be sufficient for faith; yet faith does not desire instruction”
But when you read further in this sermon (
earlychurchtexts.com/public/augustine_sermon_272_eucharist.htm) he states:
“My friends, these realities are called sacraments because in them one thing is seen, while another is grasped. What is seen is a
mere physical likeness; what is grasped bears spiritual fruit.”
I wonder if your quote on worshipping the host is from Augustine’s
Exposition of the Psalm 98?
“He walked here in very flesh, and gave that very flesh to us to eat for our salvation; and no one eats that flesh, unless he has first worshipped:
we have found out in what sense such a footstool of our Lord’s may be worshipped, and not only that we sin not in worshipping it, but that we sin in not worshipping.”
At the end of this paragraph he clarifies that it is spiritually and not carnally understood:
“Understand spiritually what I have said; you are not to eat this body which you see; nor to drink that blood which they who will crucify Me shall pour forth. I have commended unto you a certain mystery; spiritually understood, it will quicken.
Although it is needful that this be visibly celebrated, yet it must be spiritually understood.”
newadvent.org/fathers/1801099.htm
Actually Theodoret (393-457), wrote a dialogue in order to combat a heresy denying the 2 natures of Christ. In his diaglogue ‘Orthodoxos’ represents the orthodox belief while ‘Eranistes’ represents the heretic. The Eucharist is used as an example in Dialogue 2:
"Eran.— As, then, the symbols of the Lord’s body and blood are one thing before the priestly invocation, and after the invocation are changed and become another thing; so the Lord’s body after the assumption is changed into the divine substance.
Orth.— You are caught in the net you have woven yourself.
For even after the consecration the mystic symbols are not deprived of their own nature; they remain in their former substance figure and form; they are visible and tangible as they were before. But they are regarded as what they have become, and believed so to be, and are worshipped as being what they are believed to be…"
I think of what these men are stating at their time and comparing that to statements made in the Council of Trent like:
“If any one denieth, that, in the sacrament of the most holy Eucharist, are contained truly, really, and substantially, the body and blood together with the soul and divinity of our Lord Jesus Christ, and consequently the whole Christ;** but saith that He is only therein as in a sign, or in figure, or virtue; let him be anathema**.”
It seems clear that the understanding changed over the centuries. I wonder if Augustine and Theodoret taught in the 1500’s if they would be considered heretics.