The Savior counseled his disciples to see that no unworthy person partook of the sacrament, “For whoso eateth and drinketh my flesh and blood unworthily eateth and drinketh damnation to his soul.” (3 Nephi 18:29.) This same admonition that we are not to partake of the sacrament unless we are worthy and are willing to keep the commandments of the Lord has been given to us in this dispensation. (See D&C 46:4.)
Concerning the evil of partaking of the sacrament unworthily, President David O. McKay has said: “To partake of the sacrament unworthily is to take a step toward spiritual death. No man can be dishonest within himself without deadening the susceptibility of his spirit. Sin can stun the conscience as a blow on the head can stun the physical senses. He who promises one thing and deliberately fails to keep his word, adds sin to sin. On natural principles such a man ’eats and drinks condemnation to his soul.’ ” (Conference Report, October 1929, pp. 14-15.)