I dunno. Certainly there are a lot of other people who also hold that view; it would not be difficult to pick up the idea from various sources that it was actually true. I am just pointing out that it does not seem to be true. (And, of course, if it appears in a Chick Tract, it is always suspect in my mind.)
The term Transubstantiation seems to have first been used by Bishop Hildebert of Tours around 1079. It was coined (or borrowed from earlier Greek philosophy) to express a perception of what happens at the Consecration of the bread and wine.
The idea that Jesus is actually present in the Eucharist is ancient, following the passages of the institution of the Eucharist found in the synoptic Gospels (Mt 26: 26 - 28, Mk 14: 22 - 25, Lk 22: 14 - 20) and Paul’s letter to the Corinthians ( I Cor 11:23 - 27), along with the lengthy passage in John (Jn 6: 22 - 66, esp., 51 - 58). This is not to say that there have never been other opinions–it is a subject over which Christians have fought for years–but there are clearly voices in the earliest church who held that belief. It is not something that was “tacked on” at some later date.
Once there is general agreement that Jesus is present in the Eucharist, the next thing to wrangle over is “What does present in mean?” or “How is this possible?” People being people, there have been many fights over this issue, as well.
The Greek Church never got heavily into these debates (finding other things to quarrel over), but borrowing from principles laid out in Greek philosophy, the theologians of the Latin Church eventually began to express the Eucharistic change as a change in Substance. Substance (in this frame of reference) is what something really, truly is, despite whatever it may appear to be. The word transubstantiation was coined (or borrowed) to indicate that the Eucharist undergoes a change of reality physically as well as spiritually–its very nature is change from that of bread and wine (which it continues to resemble or appear as) into the Body and Blood of Jesus.
Catholic Encyclopedia - Real Presence of Christ in the Eucharist - Transubstantiation
Now, it is possible to see the whole thing as so much religious silliness, or to hold that the Eucharist is merely symbolic and the notion of the Divine Presence either foolish or blasphemous, or to hold a belief in the Divine Presence and find the arguments silly, or to find the arguments serious but the conclusions in error (depending on how far away one stands from the RCC in one’s opinions). However, when we look at the development of the concept, it is pretty clear that the RCC did not simply run out in the third or fourth century and “borrow” some ancient Egyptian belief. (I doubt that Hildebert of Tours had more than a vague notion that ancient Egyptians had an organized belief system beyond what he would have dismissed as myth.)
As to the Egyptian connection to the Eucharist, I am not sure where that began, but all the references that I can find repeat the same line–and all of them are found in sites or books attacking Catholicism, none in sites or books describing Egyptian worship.
There are a few similarities between the myth of Osiris and the beliefs held by Christians about Jesus (whether these are archetypes or borrowings, I will not speculate).
Osiris was slain unjustly, and his body hidden. His wife, Isis, discovered it, but his murderer came on Isis, took the body, and tore it into pieces, scattering it across Egypt. Isis then found all the pieces, establishing temples to honor the god at each location a body part was foud, and reassembled the body, at which point Amen-Ra resurrectd body and set Osiris up as the king of the dead.
Osiris had been a corn god, and there were some rites at the harvest of the new corn that involved lamenting the “cutting down” of the god to provide the corn to eat. Frazer’s The Golden Bough describes four separate varieties of religious rites involving the worship of Osiris and none of them mention calling bread the body of Osiris and breaking it up to be eaten by his adherents. No other work I have found describing Egyptian religions makes any mention of creating “wafers of bread” and distributing them to be eaten as the god. Those claims are always found in Christian sites attacking Catholicism (or, occasionally, on neo-pagan sites attempting to establish that Christianity is simply a nice pagan religion that got out of hand).
So we have the application of a Greek philosophical term used by Medieval theologians being applied to an Egyptian ritual for which there does not seem to be any evidence.