We actually just had a very vibrant and wholesome debate about Transubstantiation. Since that discussion strayed off of topic, the moderators closed it. However, you can read it here:
Since then I have begun to read a book I bought named “Eucharistic Miracles”. The first miracle in the book is a story about a priest in the 8th century. The priest was known for being a doubter of the Transubstantiation. As he was conducting the Consecration a piece of flesh appeared on top the unleavened bread that was to be the host and the cup of wine now was full of real blood. After the event, the blood congealed into 5 “nuggets”. Since this event the flesh and blood had been subjected to continual observation and many scientific experiments. The latest of which was in 1971 where both the blood and flesh was found to be definitively human, have an AB Blood type and the flesh was of a human’s heart. In the 1971 examination it was found that the container which held the flesh was never hermetically sealed, had no traces of any sort of preservative, yet the flesh shows no sign of decay whatsoever.
This 1300 year old piece of flesh and the 5 “nuggets” of congealed blood can be seen in a tabernacle in the Church of St. Francis in Siena, Italy.
Besides that I’d like to share with you some of the main points that John and some of us Catholics debated about in the thread linked above.
One of the main arguments of John’s was that Jesus’ statements in 1 Cor 10, 1 Cor 11, John 6 were all of a spiritual nature, that Jesus never actually meant we ought eat his flesh and drink his blood.
My main response is simply that Jesus said the things he said the way he said it because he was talking about his entire body, the spiritual as well as the physical. Additionally, Jesus would not be deceptive, he would not say he was the fruit of the vine, the sacrificial Lamb of God, the Bread of Life and then say that we must eat his flesh and drink his blood as only a spiritual aspect because that would be misleading.
Additionally, if you look at the phrases “Drink the blood of” and “Eat the flesh of” from the way that the people of Jesus’ time would have understood them, you would see that these phrases meant to ridicule or attack whoever was the direct object of the phrase. Thus the sentence Jesus spoke: “No one will get to heaven unless they eat the flesh of the Son of God” would mean “No one will get to heaven unless they ridicule the Son of God”. That does not make sense.
Thus, Jesus could not have meant this figuratively nor could he have meant it only spiritually, he meant it literally and we must believe that in some way, Jesus comes into the bread and wine at our Eucharist and that bread and wine are the real presence of Jesus.