1 Corinthians 11:27-30

So a person who eats the bread or drinks the cup of the Lord in a way that is not worthy of it will be guilty of sinning against the body and the blood of the Lord. Look into your own hearts before you eat the bread and drink the cup, because all who eat the bread and drink the cup without recognizing the body eat and drink judgment against themselves. That is why many in your group are sick and weak, and some of you have died.