Jesus said to them, "I am telling you the truth; if you do not eat the flesh of the Son of Man and drink his blood, you will not have life in yourself."
Many of his followers heard his and said, "This teaching is too hard. Who can listen to it?"
Without being told, Jesus knew that they were grumbling about this, so he said to them, "does this make you want to give up? Suppose then, that you should see the Son Of Man go back up to the place where he was before? What gives life in God's Spirit: human power is of no use at all. The words I have spoken to you bring God's life-giving Spirit. Yet some of you do not believe." (Jesus knew from the very beginning who were the ones that would not believe and which one would betray him.) And he added, "this is the very reason I told you that no people can come to me unless the Father makes it possible for them to do so".
Because of this, many of Jesus' followers turned back and would not go with him any more. So he asked the twelve disciples, "And you- would you also like to leave?".
Simon Peter answered him "Lord, to whom would we go? You have the words that give eternal life. And now we believe and know that you are the Holy One who has come from God."