1 Corinthians 11:27
Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the Body and Blood of the Lord.
It is worth noting that when Paul spoke of profaning the body and blood of the Lord, he was not speaking of pecadilloes concerning posture, but of the far more serious matter of despising our fellow Christians. The Corinthians were being grade-A bozos during their Eucharistic banquets. They were factional, they got drunk, and they routinely humiliated the poorest members of the Body of Christ. Paul warned them that to sin against the Body of Christ which is the Church is to sin against the Body of Christ in the Eucharist. Conversely, to honor the Body of Christ which is the Church is to honor the Body of Christ which is the Eucharist. Today, honor the Body of Christ — the Eucharistic Body!