John 6:59-65

He said these things in a synagogue while He was teaching in Capernaum. When many of His disciples heard this, they said, “This is a difficult and harsh and offensive statement. Who can [be expected to] listen to it?” But Jesus, aware that His disciples were complaining about it, asked them, “Does this cause you to stumble and take offense? What then [will you think] if you see the Son of Man ascending to [the realm] where He was before? It is the Spirit who gives life; the flesh conveys no benefit [it is of no account]. The words I have spoken to you are spirit and life [providing eternal life]. But [still] there are some of you who do not believe and have faith.” For Jesus knew from the beginning who did not believe, and who would betray Him. And He was saying, “This is the reason why I have told you that no one can come to Me unless it has been granted him [that is, unless he is enabled to do so] by the Father.”