John 6:63-65

63It is the spirit that giveth life; the flesh profiteth nothing: the words that I speak to you, they are spirit, and they are life. 64But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who he was that would betray him. 65And he said, Therefore I said to you, that no man can come to me, except it were given to him by my Father.