The "proclaiming" comes from 1 Corinthians 11:26: For as often as ye eat this bread, and drink this cup, ye do shew the Lord’s death till he come.
Contextually meaning by taking part in this communal meal then they were to effectually remember the Lord's death by which He purchased them ("ye are bought with a price:" 1 Corinthians 6:20) not just individually but as a body ("which he hath purchased with his own blood:" Acts 20:28 KJV), by showing love for each other in sharing food, thus acknowledging union with Christ and each other, "For we being many are one bread, and one body: for we are all partakers of that one bread," (1 Corinthians 10:17) by and in fellowship/communion with Christ.
Likewise pagans had "fellowship with with devils" (1 Corinthians 10:20) in their dedicatory feasts, which as specifically done in remembrance of the Lord's death (and thus what is signified) is a sacrificial offering, but not for sin.
However, this is not what the Corinthians were doing as a body, for instead of effectually remembering the Lord's death and thus what it signified, they were hypocritically acting contrary to it, by selfishly eating independently and to the full while effectively treating other holy blood-bought members as outcast, and thus they actually were not coming together to eat the Lord's supper:
Now in this that I declare unto you I praise you not, that ye come together not for the better, but for the worse . (1 Corinthians 11:17)
When ye come together therefore into one place, this is not to eat the Lord’s supper. For in eating every one taketh before other his own supper : and one is hungry, and another is drunken. What? have ye not houses to eat and to drink in? or despise ye the church of God, and shame them that have not ? What shall I say to you? shall I praise you in this? I praise you not. (1 Corinthians 11:20-22)
For as often as ye eat this bread, and drink this cup, ye do shew [kataggellō: preach, declare] the Lord’s death till he come. (1 Corinthians 11:26)
But let a man examine himself, and so let him eat of that bread, and drink of that cup. For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord’s body . (1 Corinthians 11:28-29)
And contextually the body which they failed to recognize was the body of Christ (which also is the subject of the next chapter, and elsewhere defines the church as the body of Christ, which the apostle Paul persecuted) by eating independently and ignoring others in need and shaming them. For we can hardly be remembering the Lord's death by which He purchased us and made the church His body if we are acting contrary to the holiness and love that Christ showed by dying for us.
This contrariness being the problem, the solution was
But let a man examine himself, and so let him eat of that bread, and drink of that cup...Wherefore, my brethren, when ye come together to eat, tarry one for another. And if any man hunger, let him eat at home; that ye come not together unto condemnation. And the rest will I set in order when I come. (1 Corinthians 11:28,33-34)
And even if we are not Catholics who focus is on receiving their wafer-god (and some resent interaction with other members during their service), or acting contrary to effectually remembering the Lord's death as blatantly as the Corinthians were - which also includes commitment to the holy character it is supposed to have (If any man defile the temple of God, him shall God destroy; for the temple of God is holy, which temple ye are: 1 Corinthians 3:17), at best I think we too often remember the Lord's death abstractly from what it accomplished as regards making us one body of believers purchased by the sinless shed blood of Christ. At least I come short in it.
Well and truly stated. Amen
“However, this is not what the Corinthians were doing as a body, for instead of effectually remembering the Lord’s death and thus what it signified, they were hypocritically acting contrary to it, by selfishly eating independently and to the full while effectively treating other holy blood-bought members as outcast, and thus they actually were not coming together to eat the Lord’s supper:” They were failing to discern the Body of Christ of which they were but a member and the one’s they were shunning also members.
Indeed. And “where two or three are gathered in My Name, I am in the midst”. The Body of Christ in many folds, but one flock.