FIRST
In several pagan traditions, authorities treated images and statues as literally embodying the deity, rather than merely representing it. In ancient Mesopotamia, for example, priests performed rituals such as the “opening of the mouth” to ensure that a statue of a god truly housed the divine presence, feeding and clothing it as if it were alive. Similarly, in ancient Egypt, cult statues of gods like Amun-Ra or Osiris were ritually infused with the deity through daily offerings and prayers, and the statues were understood as the actual manifestation of the god in the temple. Greco-Roman practices were somewhat more nuanced: some cult images were believed to contain the divine essence (numen), and while they were sometimes treated as symbolic, in many cases they were venerated as genuinely inhabited by the deity. Across these cultures, the physical object was not merely a representation but a locus of divine presence, conceptually akin to how Catholic theology regards the Eucharist as truly containing Christ in transubstantiation.
THE ARGUMENT
The Roman Catholic Church says that God can turn bread and wine into his Son Jesus. The result is that they are not bread and wine at all any more but Jesus. This doctrine is called transubstantiation - it became official and final in 1215. It is sometimes called the Real Presence. The Real Presence means Jesus's presence in its fullest sense body, blood, soul and divinity.
God performs this change when the Catholic priest blesses bread and wine on the altar at Mass.
The "accidents" ie look, smell, weight, colour and taste do not change but the underlying reality does. This gives rise to three miracles:
One is the change of bread into the body and the blood of Jesus.
Two is how this is done without anything physically changing.
Three is that it is a miracle for bread and wine to be alive. They become a living being. The multiplication of miracles shows that there is something wildly superstitious and credulous about all that.
That is a lot of trouble for feeding on Jesus for fifteen minutes. If he leaves his graces on the soul after, what does he even need to go to all that trouble for?
There are other considerations.
An eye exists to see. If an eye were somehow turned into a marble, it would no longer be an eye because it could no longer perform its essential function of seeing. Similarly, if a marble were said to become an eye without gaining the ability to see, it would still be a marble. The essential powers of a thing define what it is. Applied to the Eucharist, if the bread is said to become Jesus but retains none of the properties of a human being, it cannot truly be Jesus in any meaningful sense. In practice, worshiping the wafer is worshiping bread, because the physical and functional reality of Jesus is not present.
Aristotle distinguished substance from accidents, but he never suggested that a substance could change while its matter remains the same. He wrote, “A substance is generated (destroyed) by having matter take on (lose) form” (Metaphysics Zeta 17), meaning that any change in substance involves a change in the underlying matter. The Catholic doctrine of transubstantiation—where the bread’s substance becomes Christ while its accidents remain—contradicts this principle, because Aristotle held that the essence of a thing cannot exist independently of its material form.
If the bread remains entirely physically identical after consecration—same structure, chemistry, behavior, and causal powers—then the claim that it is “no longer bread” but is now Jesus does not describe a meaningful change in the world. A change that produces no detectable difference in physical reality is indistinguishable from an imagined or purely verbal change.
To avoid this problem, one must assume that bread has some non-physical essence or “soul” that makes it bread, and that this essence is replaced by Jesus. But this move introduces two serious consequences:
It treats material objects as if they have non-physical identities independent of their physical properties, which is metaphysically controversial and unexplained.
It separates Jesus from physicality, making his presence non-physical rather than embodied—undermining or bypassing the Christian claim that Jesus is incarnate (fully physical and material).
Thus, either nothing real changes (making the doctrine meaningless), or the doctrine relies on an implausible metaphysics of non-physical essences, or it collapses into a view where Jesus is present only abstractly, not physically.
Whatever Jesus meant when he said we must gnaw his flesh as food it certainly was not anything like the Catholic doctrine which claims that bread turns into Jesus' flesh but doesn't claim it in any meaningful sense or in a way that makes any sense. Given the rule of reason that no book should be interpreted in an unreasonable way, it follows that if the Bible does say the bread/wine is Jesus it means it metaphorically. Catholics deny this. If the world at the time of Christ made a difference between substance and accidents and imagined one changing without the other changing and this teaching made sense it would be different. But it didn't.
APPENDIX:
Michael J Langford wrote, "It is worth insisting at this point that there is no need for Roman Catholics and other Christians to be divided on this matter, despite the controversy which has raged over 'transubstantiation' (the Roman Catholic doctrine that the bread and wine become in substance the body and blood of Christ). Recent studies have shown how much this old controversy is based on misunderstanding. The thing to remember here is that the definition of the doctrine is in Latin and there has been a tendency to use inappropriate English words in the translation. Thus while the doctrine asserts that there is a change in substance, it also asserts that the 'accidents' of sight, taste, touch, etc., are unchanged. In Modern English, it is precisely these things that signify the physical nature of something, so that it would be more accurate to say that the bread and wine were physically unchanged than to say that they were changed" page 69, Unblind Faith, Michael J Langford, SCM Press, London, 1982).