1 Corinthians 11:27-30

Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be answerable for the body and blood of the Lord. Examine yourselves, and only then eat of the bread and drink of the cup. For all who eat and drink without discerning the body, eat and drink judgment against themselves. For this reason many of you are weak and ill, and some have died.