After hearing it, many of his followers said, ‘This is intolerable language. How could anyone accept it?’ Jesus was aware that his followers were complaining about it and said, ‘Does this disturb you? What if you should see the Son of man ascend to where he was before? ‘It is the spirit that gives life, the flesh has nothing to offer. The words I have spoken to you are spirit and they are life.‘But there are some of you who do not believe.’ For Jesus knew from the outset who did not believe and who was to betray him.He went on, ‘This is why I told you that no one could come to me except by the gift of the Father.’After this, many of his disciples went away and accompanied him no more.Then Jesus said to the Twelve, ‘What about you, do you want to go away too?’Simon Peter answered, ‘Lord, to whom shall we go? You have the message of eternal life, and we believe; we have come to know that you are the Holy One of God.’
What is to be understood in the above passage is in bold.