This Sunday, my family and I are getting chrismated (plus baptism for kids) into the Holy Orthodox Catholic Church, and we will all be receiving the Eucharist for the very first time in our lives. The Eucharist is the normal means Christ established to unite us to Himself in the blood of the new covenant. It is the medicine of immortality. It is the very blood that was shed for us - not a new sacrifice, but always proclaiming the same sacrifice. It has real power through Christ to sanctify us and keep us in union with Him, and is *necessarily* understood to truly be the body and blood of Christ after the prayers are said over it to sanctify the bread and wine. In this way, among other ways as well, we can truly say that Christ is our sanctification.
"And this food is called among us Εὐχαριστία [the Eucharist], of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing [baptism] that is for the remission of sins, and unto regeneration, and who is so living as Christ has enjoined. For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Savior, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh." Justin Martyr's First Apology, 150AD.
"Obey the bishop and the presbytery with an undivided mind, breaking one and the same bread, which is the medicine of immortality, and the antidote to prevent us from dying, but which causes that we should live for ever in Jesus Christ." Ignatius, 110AD.
"Do not err, my brethren. If any man follows him that makes a schism in the Church, he shall not inherit the kingdom of God. If any one walks according to a strange opinion, he agrees not with the passion of Christ. 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 [in each city], along with the presbytery and deacons, my fellow-servants: that so, whatsoever you do, you may do it according to the will of God." Ignatius, 110AD.
"They abstain from the Eucharist and from prayer, because they confess not the Eucharist to be the flesh of our Savior Jesus Christ, which suffered for our sins, and which the Father, of His goodness, raised up again. Those, therefore, who speak against this gift of God, incur death in the midst of their disputes. But it were better for them to treat it with respect, that they also might rise again." Ignatius, 110AD.
"Drink from it, all of you. For this is My *blood of the new covenant*, which is shed for many for the remission of sins." Matthew 26:28
"Of how much worse punishment, do you suppose, will he be thought worthy who has trampled the Son of God underfoot, counted the *blood of the covenant* by which he was sanctified **a common thing**, and insulted the Spirit of grace?" Hebrews 10:29
"Now may the God of peace who brought up our Lord Jesus from the dead, that great Shepherd of the sheep, through the *blood of the everlasting covenant*, make you complete in every good work to do His will, working in you what is well pleasing in His sight, through Jesus Christ, to whom be glory forever and ever. Amen." Hebrews 13:20.
"For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one. And there are three that bear witness on earth: the Spirit, the water [baptism], and the blood [Eucharist]; and these three agree as one." 1 John 5:7-8