60 Many among his disciples heard this and said, "This is tough teaching, too tough to swallow." 61 Jesus sensed that his disciples were having a hard time with this and said, "Does this throw you completely? 62 What would happen if you saw the Son of Man ascending to where he came from? 63 The Spirit can make life. Sheer muscle and willpower don't make anything happen. Every word I've spoken to you is a Spirit-word, and so it is life-making. 64 But some of you are resisting, refusing to have any part in this." (Jesus knew from the start that some weren't going to risk themselves with him. He knew also who would betray him.) 65 He went on to say, "This is why I told you earlier that no one is capable of coming to me on his own. You get to me only as a gift from the Father."
Matthew Henry's Commentary on John 6:60-65
Commentary on John 6:60-65
(Read John 6:60-65)
The human nature of Christ had not before been in heaven, but being God and man, that wondrous Person was truly said to have come down from heaven. The Messiah's kingdom was not of this world; and they were to understand by faith, what he had said of a spiritual living upon him, and his fulness. As without the soul of man the flesh is of no value, so without the quickening Spirit of God all forms of religion are dead and worthless. He who made this provision for our souls, alone can teach us these things, and draw us unto Christ, that we may live by faith in him. Let us apply to Christ, thankful that it is declared that every one who is willing to come unto him shall be made welcome.