Some years ago, the late Reverend Ian Paisley, the staunchly anti-Catholic head of the Free Presbyterian Church of Ulster, was debating his position at the Oxford Union, a renowned debating society, when he pulled out a piece of communion bread and declared that Catholics believe that this is Christ. Well, I hope that he had not got his hands on a consecrated host, but in any case,like all propagandists he was thinking in caricatures. While the church has an explanation of the real presence of Christ in the Eucharist, it acknowledges that the Eucharist is a profound mystery, the full understanding of which is beyond human comprehension. So yes,it is the body of Christ, but in a mysterious way far beyond the simplistic posturings of the likes of Dr Paisley.
We adhere to this doctrine because we get it from Jesus.The gospels tell how at the Last Supper Jesus took the bread and wine and declared that they were his body and blood.In other words they were to be his physical manifestation when he had gone from sight.The breaking of bread and the Lord's Supper are mentioned in the Acts of the Apostles and the Pauline letters, so this shows that the Eucharist was central to the life of the church,which regarded it as the visible manifestation of Christ to his people.
However, one thing must be emphasised. It is not the body of Christ as he was when he walked in Israel, that is believed to be present, but the risen Christ who at the resurrection acquired a glorified body that transcended earthly limitations that is present. We note from the resurrection stories in the gospels that after the resurrection Jesus seems to have been free of physical constraints and at time was not recognisable even by his close companions, and in the light of this liberation it becomes less surprising that the church accepts that Jesus becomes manifest as the Eucharistic elements of bread and wine.
Some find it incredible that Catholics can seemingly fly in the face of commonsense,for surely bread cannot be a body, and they see the Eucharist as merely a memorial. But common sense is not a good guide to reality,for the world revealed by physics is far from commonsensical, and reality can be very strange to us. Can it be so surprising that God is even stranger than the created universe is? Furthermore, when at the Last Supper Jesus said "Do this in memorial of me he used the word anamnesis, which means more than simple remembering, but reliving,making present again, so Jesus was implying that he would continue to be among his disciples through the Eucharistic elements of bread and wine after his departure.
The Christian church has tried to find a philosophical formulation for the real presence of Christ in the Eucharist. Roman Catholicism uses the term transubtantiation, which mean that the substance of bread and wine are changed but their appearances have not. Some other churches use consubstantiation,meaning that the elements remain bread and wine, but become linked to the risen Christ. It is possible to argue for hours about this issue, but what matters is the real presence of Christ among his people.