The doctrine of the Eucharist has been held from
the very earliest days of the Church. For the first 800 years
of Christianity, there was no doubt regarding the Real Presence
of Christ in the Eucharist. Here is a sample of writings from
the fathers of the early Church illustrating this.
Paul writing in 1 Cor 10:15-16
"I speak to sensible people; judge for yourselves
what I say. Is not the cup of thanksgiving for which we give
thanks a participation in the blood of Christ? And is not the
bread that we break a participation in the body of Christ?"
Paul writing in 1 Cor 11:23-30
"For I received from the Lord what I also passed
on to you: The Lord Jesus, on the night he was betrayed, took
bread, and when he had given thanks, he broke it and said, "This
is my body, which is for you; do this in remembrance of me."
In the same way, after supper he took the cup, saying, "This
cup is the new covenant in my blood; do this, whenever you drink
it, in remembrance of me." For whenever you eat this bread
and drink this cup, you proclaim the Lord's death until he comes.
Therefore, whoever eats the bread or drinks the cup of the Lord
in an unworthy manner will be guilty of sinning against the body
and blood of the Lord. A man ought to examine himself before
he eats of the bread and drinks of the cup. For anyone who eats
and drinks without recognizing the body of the Lord eats and drinks
judgment on himself."
Ignatius of Antioch, 110 AD
"They abstain from the Eucharist and from prayer,
because they do not confess that the Eucharist is the flesh of
our savior Jesus Christ, flesh which suffered for our sins and
which the Father, in his goodness, raised up again... Let that
be considered a valid Eucharist which is celebrated by the bishop,
or by one whom he appoints. Wherever the bishop appears, let
the people be there; just as wherever Jesus Christ is, there
is the Catholic Church." (Epistle to the Smyreans)
"Take heed, then, to have but one Eucharist.
For there is one flesh of our Lord Jesus Christ, and one cup to
[show forth] the unity of His blood; one altar; as there is one
bishop, along with the presbytery and deacons, my fellow-servants:
that so, whatsoever you do, you may do it according to [the will
of] God." (Epistle to the Philadelphians)
Justin Martyr, 150 AD
"We call this food Eucharist, and no one else
is permitted to partake of it, except one who believes our teaching
to be true and who has been washed in the washing which is for
the remission of sins and for regeneration and is thereby living
as Christ has enjoined. For not as common bread nor common drink
do we receive these; but since Jesus Christ our Savior was made
incarnate by the word of God and had both flesh and blood for
our salvation, so too, as we have been taught, the food which
has been made into the Eucharist by the Eucharistic prayer set
down by him, and by the change of which our blood and flesh is
nourished, is both the flesh and the blood of that incarnated
Jesus." (First Apology of Justin)
Irenaeus of Lyons, 190 AD
"Christ has declared the cup... to be his own Blood, from which he causes our blood to flow; and the bread, a part of creation, he has established as his own Body, from which he gives increase to our bodies. If the Lord were from other than the Father, how could he rightly take bread, which is of the same creation as our own, and confess it to be his body and affirm that the mixture in the cup is his blood?" (Against Heresies Book V)