John 6:62

If you cannot believe that I can give you my flesh to eat, now that I am living amongst you, how will you believe, that, after my ascension, I can give you to eat my glorified and immortal flesh, seated on the right hand of the majesty of God? (Bible de Vence)

Christ, though clothed with our flesh, yet being also the eternal Son of God, knew by virtue of his Divine nature, personally united to the human nature, what was in the heart of man; hence is this phrase, which is opposed to a knowledge from the hearing of his own ears, as man heareth, whether more immediately from the sound of their words, (for we read of nothing they spake audibly), or from the relation of others, as what they had heard: he knew in himself their thoughts by his Divine prerogative and property of searching the hearts, and trying the reins, and discerning the thoughts of men afar off. Knowing their thoughts, he saith, Doth this give you occasion of stumbling?

[1.] He gives them a hint of his ascension into heaven, as that which would give an irresistible evidence of the truth of his doctrine (v. 62): What and if you shall see the Son of man ascend up where he was before? And what then? First, "If I should tell you of that, surely it would much more offend you, and you would think my pretensions too high indeed. If this be so hard a saying that you cannot hear it, how will you digest it when I tell you of my returning to heaven, whence I came down?" See ch. 3 12. Those who stumble at smaller difficulties should consider how they will get over greater. Secondly, "When you see the Son of man ascend, this will much more offend you, for then my body will be less capable of being eaten by you in that gross sense wherein you now understand it;" so Dr. Whitby. Or, Thirdly, "When you see that, or hear it from those that shall see it, surely then you will be satisfied. You think I take too much upon me when I say, I came down from heaven, for it was with this that you quarrelled (v. 42); but will you think so when you see me return to heaven?" If he ascended, certainly he descended, Eph 4 9, 10. Christ did often refer himself thus to subsequent proofs, as ch. 1 50, 51; 2 14; Matt 12 40; 26 64. Let us wait awhile, till the mystery of God shall be finished, and then we shall see that there was no reason to be offended at any of Christ's sayings.

Verses 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.