John 6:60-65

60 Then, hearing this, a number of his disciples said, This is a hard saying; who is able to take in such teaching?

61 When Jesus became conscious that his disciples were protesting about what he said, he said to them, Does this give you trouble?

62 What then will you say if you see the Son of man going up to where he was before?

63 The spirit is the life giver; the flesh is of no value: the words which I have said to you are spirit and they are life.

64 But still some of you have no faith. For it was clear to Jesus from the first who they were who had no faith, and who it was who would be false to him.

65 And he said, This is why I said to you, No man is able to come to me if he is not given the power to do so by the Father.