John 6:66 Meaning

64But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who should betray him.

65And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father.

66From that time many of his disciples went back, and walked no more with him.

67Then said Jesus unto the twelve, Will ye also go away?

68Then Simon Peter answered him, Lord, to whom shall we go? thou hast the words of eternal life.