1 Corinthians 11:27-30 NIV

[27] So then, whoever eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of sinning against the body and blood of the Lord. [28] Everyone ought to examine themselves before they eat of the bread and drink from the cup. [29] For those who eat and drink without discerning the body of Christ eat and drink judgment on themselves. [30] That is why many among you are weak and sick, and a number of you have fallen asleep.