You mean these words?
John 6:63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.
Of course we believe them. Why don't Catholocs?
I was thinking more along the line of ..unless you eat of the flesh of the Son of man and drink of His blood, you shall not have life within you.....or take and eat of this, this is My Body...etc.