Even of itself the teaching of the Blessed Paul is sufficient to give you a full assurance concerning those Divine Mysteries, of which having been deemed worthy, you have become of the same body and blood with Christ. For you have just heard him say distinctly, “that our Lord Jesus Christ on the night when He was betrayed took bread, and when he had given thanks, He broke it, gave to His disciples and said, ‘This is my body’. And having taken and given thanks, he said, “Take, drink, this is my blood.”. Since then He Himself declared and said of the Bread, “This is My Body,” who shall dare to doubt any longer? And since He has Himself affirmed and said, “This is My Blood,” who shall ever hesitate and say that it is not His blood?
He once turned the water into wine, akin to blood, in Cana of Galilee, and is it incredible that He should have turned wine into blood? When called to an earthly wedding, He miraculously wrought that wonderful work; should we not much more confess that He has given the enjoyment of His Body and Blood to His wedding guests [Mark 2:19]?
Therefore, let us partake of the Body and Blood of Christ with full assurance: for in the figure of Bread His Body is given to you, and His Blood in the figure of Wine, so that by partaking of the Body and Blood of Christ, you may be made to be of the same body and the same blood with Him. For thus we come to bear Christ in us, because His Body and Blood are distributed through our members; thus it is that, according to the blessed Peter, we become partakers of the divine nature [2 Peter 1:4].
Cyril of Jerusalem, ‘The Mysteries’ IV.2. Adapted from Philip Schaff (ed.), Nicene and Post-Nicene Fathers, Series II, Vol. 7 (New York: Christian Literature Publishing Company, 1893), 151.