St Paul 1 Cor 10:16-17 and 1 Cor 11:23-27
Ignatius of Antioch
“Consider how contrary to the mind of God are the heterodox in regard to the grace of God which has come to us. They abstain from the Eucharist and from prayer, because they do not admit that the Eucharist is the flesh of our Savior Jesus Christ, the flesh which suffered for our sins and which the Father, in His graciousness, raised from the dead.” “Letter to the Smyrnaeans”, paragraph 6. circa 80-110 A.D.
“I want the Bread of God which is the Flesh of Christ, who was the seed of David; and for drink I desire His Blood which is love that cannot be destroyed.” “Letter to the Romans”, paragraph 7, circa 80-110 A.D.
“Who belongs to God and to Jesus Christ - they are with the bishop. And those who repent and come to the unity of the Church - they too shall be of God, and will be living according to Jesus Christ. Do not err, If any man walk about with strange doctrine, he cannot lie down with the passion. Take care, then, to use one Eucharist, so that whatever you do, you do according to God: for there is one Flesh of our Lord Jesus Christ, and one cup in the union of His Blood; one altar, as there is one bishop with the presbytery and my fellow servants, the deacons.” “Epistle to the Philadelphians”, 3:2-4:1, 110 A.D.
Justyn Martyr
“This food we call the Eucharist, of which no one is allowed to partake except one who believes that the things we teach are true, and has received the washing for forgiveness of sins and for rebirth, and who lives as Christ handed down to us. For we do not receive these things as common bread or common drink; but as Jesus Christ our Savior being incarnate by God’s Word took flesh and blood for our salvation, so also we have been taught that the food consecrated by the Word of prayer which comes from him, from which our flesh and blood are nourished by transformation, is the flesh and blood of that incarnate Jesus.” “First Apology”, Ch. 66, inter A.D. 148-155.
Irenaeus of Lyons
“So then, if the mixed cup and the manufactured bread receive the Word of God and become the Eucharist, that is to say, the Blood and Body of Christ, which fortify and build up the substance of our flesh, how can these people claim that the flesh is incapable of receiving God’s gift of eternal life, when it is nourished by Christ’s Blood and Body and is His member? As the blessed apostle says in his letter to the Ephesians, ‘For we are members of His Body, of His flesh and of His bones’ (Eph. 5:30). He is not talking about some kind of ‘spiritual’ and ‘invisible’ man, ‘for a spirit does not have flesh an bones’ (Lk. 24:39). No, he is talking of the organism possessed by a real human being, composed of flesh and nerves and bones. It is this which is nourished by the cup which is His Blood, and is fortified by the bread which is His Body. The stem of the vine takes root in the earth and eventually bears fruit, and ‘the grain of wheat falls into the earth’ (Jn. 12:24), dissolves, rises again, multiplied by the all-containing Spirit of God, and finally after skilled processing, is put to human use. These two then receive the Word of God and become the Eucharist, which is the Body and Blood of Christ.” Five Books on the Unmasking and Refutation of the Falsely
“For just as the bread which comes from the earth, having received the invocation of God, is no longer ordinary bread, but the Eucharist, consisting of two realities, earthly and heavenly, so our bodies, having received the Eucharist, are no longer corruptible, because they have the hope of the resurrection.” Book 4:18 4-5, circa 180 A.D.
Clement of Alexandria
“The Blood of the Lord, indeed, is twofold. There is His corporeal Blood, by which we are redeemed from corruption; and His spiritual Blood, that with which we are anointed. That is to say, to drink the Blood of Jesus is to share in His immortality. The strength of the Word is the Spirit just as the blood is the strength of the body. Similarly, as wine is blended with water, so is the Spirit with man. The one, the Watered Wine, nourishes in faith, while the other, the Spirit, leads us on to immortality. The union of both, however, - of the drink and of the Word, - is called the Eucharist, a praiseworthy and excellent gift. Those who partake of it in faith are sanctified in body and in soul. By the will of the Father, the divine mixture, man, is mystically united to the Spirit and to the Word.”, “The Instructor of the Children”. [2,2,19,4] ante 202 A.D.,
Ephraim of the Syrian Church
"Our Lord Jesus took in His hands what in the beginning was only bread; and He blessed it, and signed it, and made it holy in the name of the Father and in the name of the Spirit; and He broke it and in His gracious kindness He distributed it to all His disciples one by one. He called the bread His living Body, and did Himself fill it with Himself and the Spirit.,
And extending His hand, He gave them the Bread which His right hand had made holy: ‘Take, all of you eat of this; which My word has made holy. Do not now regard as bread that which I have given you; but take, eat this Bread, and do not scatter the crumbs; for what I have called My Body, that it is indeed. One particle from its crumbs is able to sanctify thousands and thousands, and is sufficient to afford life to those who eat of it. Take, eat, entertaining no doubt of faith, because this is My Body, and whoever eats it in belief eats in it Fire and Spirit. But if any doubter eat of it, for him it will be only bread. And whoever eats in belief the Bread made holy in My name, if he be pure, he will be preserved in his purity; and if he be a sinner, he will be forgiven.’ But if anyone despise it or reject it or treat it with ignominy, it may be taken as certainty that he treats with ignominy the Son, who called it and actually made it to be His Body.", “Homilies” 4,4 ca… 350 A.D., [
therealpresence.org]