The Sacrament of the Altar
Q63. Who receives this sacrament worthily?
Fasting and bodily preparation are certainly fine outward training. But that person is truly worthy and well prepared who has faith in these words: "Given and shed for you for the forgiveness of sins." But anyone who does not believe these words or doubts them is unworthy and unprepared, for the words "for you" require all hearts to believe.
Scripture Proofs — King James Version
1
1 Corinthians 11:27–29
Hebrews 11:6
2 Corinthians 13:5
“Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?”
Read Luther’s expanded teaching
From the Large Catechism (1529)