Chapter II. – When Christ visited us in His grace, He did not come to what did not belong to Him: also, by shedding His true blood for us, and exhibiting to us His true flesh in the Eucharist, He conferred upon our flesh the capacity of salvation.
1. And vain likewise are those who say that God came to those things which did not belong to Him, as if covetous of another’s property; in order that He might deliver up that man who had been created by another, to that God who had neither made nor formed anything, but who also was deprived from the beginning of His own proper formation of men. The advent, therefore, of Him whom these men represent as coming to the things of others, was not righteous; nor did He truly redeem us by His own blood, if He did not really become man, restoring to His own handiwork what was said [of it] in the beginning, that man was made after the image and likeness of God; not snatching away by stratagem the property of another, but taking possession of His own in a righteous and gracious manner. As far as concerned the apostasy, indeed, He redeems us righteously from it by His own blood; but as regards us who have been redeemed, [He does this] graciously. For we have given nothing to Him previously, nor does He desire anything from us, as if He stood in need of it; but we do stand in need of fellowship with Him. And for this reason it was that He graciously poured Himself out, that He might gather us into the bosom of the Father.
2. But vain in every respect are they who despise the entire dispensation of God, and disallow the salvation of the flesh, and treat with contempt its regeneration, maintaining that it is not capable of incorruption. But if this indeed do not attain salvation, then neither did the Lord redeem us with His blood, nor is the cup of the Eucharist the communion of His blood, nor the bread which we break the communion of His body. 1 Cor. x. 16. For blood can only come from veins and flesh, and whatsoever else makes up the substance of man, such as the Word of God was actually made. By His own blood he redeemed us, as also His apostle declares, “In whom we have redemption through His blood, even the remission of sins.” Col. i. 14. And as we are His members, we are also nourished by means of the creation (and He Himself grants the creation to us, for He causes His sun to rise, and sends rain when He wills Matt. v. 45. ). He has acknowledged the cup (which is a part of the creation) as His own blood, from which He bedews our blood; and the bread (also a part of the creation) He has established as His own body, from which He gives increase to our bodies.
3. When, therefore, the mingled cup and the manufactured bread receives the Word of God, and the Eucharist of the blood and the body of Christ is made,from which things the substance of our flesh is increased and supported, how can they affirm that the flesh is incapable of receiving the gift of God, which is life eternal, which [flesh] is nourished from the body and blood of the Lord, and is a member of Him?—even as the blessed Paul declares in his Epistle to the Ephesians, that “we are members of His body, of His flesh, and of His bones.”Eph. v. 30. He does not speak these words of some spiritual and invisible man, for a spirit has not bones nor flesh; Luke xxiv. 39. but [he refers to] that dispensation [by which the Lord became] an actual man, consisting of flesh, and nerves, and bones,—that [flesh] which is nourished by the cup which is His blood, and receives increase from the bread which is His body. And just as a cutting from the vine planted in the ground fructifies in its season, or as a corn of wheat falling into the earth and becoming decomposed, rises with manifold increase by the Spirit of God, who contains all things, and then, through the wisdom of God, serves for the use of men, and having received the Word of God, becomes the Eucharist, which is the body and blood of Christ; so also our bodies, being nourished by it, and deposited in the earth, and suffering decomposition there, shall rise at their appointed time, the Word of God granting them resurrection to the glory of God, even the Father, who freely gives to this mortal immortality, and to this corruptible incorruption, 1 Cor. xv. 53. because the strength of God is made perfect in weakness, 2 Cor. xii. 3. in order that we may never become puffed up, as if we had life from ourselves, and exalted against God, our minds becoming ungrateful; but learning by experience that we possess eternal duration from the excelling power of this Being, not from our own nature, we may neither undervalue that glory which surrounds God as He is, nor be ignorant of our own nature, but that we may know what God can effect, and what benefits man receives, and thus never wander from the true comprehension of things as they are, that is, both with regard to God and with regard to man. And might it not be the case, perhaps, as I have already observed, that for this purpose God permitted our resolution into the common dust of mortality, that we, being instructed by every mode, may be accurate in all things for the future, being ignorant neither of God nor of ourselves? Source: Against Heresies, Book 5, Chapter 2, by Irenaeus (120–202)