Jesus could likely have not said anything more offensive to the human mind , especially the Jewish mind, than this in John 6:48-58. It occasioned the leaving of 70+ disciples , prompting Jesus to ask the closest 12 if they were leaving too. However, it was the custom of teachers in that day to teach by making mystical and dark sayings to prompt critical thinking . Socrates (c. 400 BC) used this so often that it is called the Socratic Method. However as you down through the passage you realize that Jesus never asked us to eat and drink of Him literally, but spiritually. He was speaking of His words and teachings as His flesh ( v63), and the coming Spirit as His Blood life ( see John 4:14; 7:37-39). We need His doctrine to guide us, but far more, His Spirit to cleanse, energize , keep, and empower us ( II Timothy 1:14). The Lord’s table does not literally fulfill this , but amply symbolizes these two treasures we have: Jesus Christ’s holiness within ( resulting in an holy life without)and power within.