Tim Staples – Catholic Answers Article –
Paul says they are “guilty of the body and blood of the Lord.” According to Numbers 35:27, Deuteronomy 21:8, 22:8, Ezekiel 35:6 and elsewhere in Scripture, to be “guilty of blood” means you are guilty of shedding innocent blood in murder. This is not the language of pure symbolism. This is the language of real presence.
“Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For anyone who eats and drinks without discerning the body eats and drinks judgment upon himself.” (1 Corinthians. 11:27-29).
Think about it: If someone were to put a bullet through a picture of a real person, I am sure the person represented in the photo would not be thrilled about it, but the perpetrator would not be “guilty of blood.” But if this same perpetrator were to put a bullet through the actual person you better believe he would be “guilty of blood.” And that’s what Paul is saying in a manner of speaking: you better believe!
Thus, the language used here in 1 Corinthians 11 is very strong—some of the strongest language St. Paul could have used, in fact—to underscore the truth that when he says we must “discern the body” here in the Eucharist, he means we must “discern the body” here in the Eucharist! This is conclusive evidence of the real presence of our Lord!