From that time many of his disciples went back. The Evangelist now relates what trouble was the consequence of that sermon. It is a dreadful and monstrous thing, that so kind and gracious an invitation of Christ could have alienated the minds of many, and especially of those who had formerly professed to belong to him, and were even his ordinary disciples. But this example is held out to us for a mirror, as it were, in which we may perceive how great is the wickedness and ingratitude of men, who turn a plain road into an occasion of stumbling to them, that they may not come to Christ. Many would say that it would have been better that a sermon of this kind should never have been preached, which occasioned the apostacy of many. But we ought to entertain a widely different view; for it was then necessary, and now is daily necessary, that what had been foretold concerning Christ should be perceived in his doctrine, namely, that he is the stone of stumbling, (Isaiah 8:14.) We ought, indeed, to regulate our doctrine in such a manner that none may be offended through our fault; as far as possible, we ought to retain all; and, in short, we ought to take care that we do not, by talking inconsiderately or at random, [1] disturb ignorant or weak minds. But it will never be possible for us to exercise such caution that the doctrine of Christ shall not be the occasion of offense to many; because the reprobate, who are devoted to destruction, suck venom from the most wholesome food, and gall from honey. The Son of God undoubtedly knew well what was useful, and yet we see that he cannot avoid [2] offending many of his disciples. Whatever then may be the dislike entertained by many persons for pure doctrine, still we are not at liberty to suppress it. Only let the teachers of the Church remember the advice given by Paul, that the word of God ought to be properly divided, (2-Timothy 2:15;) and next let them advance boldly amidst all offenses. And if it happen that many apostatize, let us not be disgusted at the word of God, because it is not relished by the reprobate; for they who are so much shaken by the revolt of some that, when those persons fall away, they are immediately discouraged, are too delicate and tender. And walked no more with him. When the Evangelist adds these words, he means that it was not a complete apostacy, but only that they withdrew from familiar intercourse with Christ; and yet he condemns them as apostates. Hence we ought to learn that we cannot go back a foot breadth, without being immediately in danger of falling into treacherous denial of our Master.

Footnotes

1 - "Inconsiderement, ou a la volee."

2 - "Il ne peut eviter."

Many of his disciples - Many who had followed him professedly as his disciples and as desirous of learning of him. See the notes at John 6:60.
Went back - Turned away from him and left him. From this we may learn,
1. Not to wonder at the apostasy of many who profess to be followers of Christ. Many are induced to become his professed followers by the prospect of some temporal benefit, or under some public excitement, as these were; and when that temporal benefit is not obtained, or that excitement is over, they fall away.
2. Many may be expected to be offended by the doctrines of the gospel. Having no spirituality of mind, and really understanding nothing of the gospel, they may be expected to take offence and turn back. The best way to understand the doctrines of the Bible is to be a sincere Christian, and aim to do the will of God, John 7:17.
3. We should examine ourselves. We should honestly inquire whether we have been led to make a profession of religion by the hope of any temporal advantage, by any selfish principle, or by mere excited animal feeling. If we have it will profit us nothing, and we shall either fall away of ourselves, or be cast away in the great day of judgment.

Many of his disciples went back - They no longer associated with him, nor professed to acknowledge him as the Messiah. None of these were of the twelve. Christ had many others who generally attended his ministry, and acknowledged him for the Messiah.

(15) From that [time] many of his disciples went back, and walked no more with him.
(15) Such is the malice of men, that they bring about their own destruction, even in hearing the very doctrine of salvation, but there are a few who believe through the singular gift of God.

From that time many of his disciples went back,.... Not any of the twelve apostles, for they are distinguished from these in the next verse; nor any of the seventy disciples, for their names were written in heaven, and could not apostatize totally and finally, as these did; but some of the multitude of the disciples, who followed Christ, heard him, and professed to believe in him, and were baptized in his name, but were not true disciples, only nominal ones: they had never heard and learned of the Father, otherwise they would have known what it was to come to Christ, as the Father's gift, and under the drawings of his grace; and would not have been offended at the words of our Lord, just now spoken by him, concerning that sort of coming to him: but from the time he spoke those words; "because of this word", as the Syriac, Arabic, and Persic versions render it; they withdrew themselves from his ministry, they dropped their profession of faith in him, and relinquished him as a Saviour and Redeemer: for finding that he would not be made king, nor set up for a temporal redeemer; and talking of himself as the bread of life, and of coming to him, in a sense they did not understand; they turned their backs on him; and as the words may be literally read, "returned to the things that were behind"; to the world, and to their old companions, to Satan and their own hearts lusts; like the dog to its vomit, and the swine to its wallowing in the mire: their true picture is drawn, in the parable of the unclean spirit going out of the man, and returning, Matthew 12:43. And they returned to their quondam teachers, the Scribes and Pharisees, and to the law of works, and to seek for righteousness by it; setting up their own righteousness, and not submitting to the righteousness of Christ; and thus to look back and draw back, is a sad case indeed:
and walked no more with him; never returned to him more, or went with him from place to place as before: never more attended on his ministry, or had any intimacy and fellowship with him: and so it commonly is with apostates from the profession of Christ; they seldom or ever return, or are recovered; it is difficult, if not impossible, which is sometimes the case, to renew them again to repentance.

When we admit into our minds hard thoughts of the words and works of Jesus, we enter into temptation, which, if the Lord in mercy prevent not, will end in drawing back. The corrupt and wicked heart of man often makes that an occasion for offence, which is matter of the greatest comfort. Our Lord had, in the foregoing discourse, promised eternal life to his followers; the disciples fastened on that plain saying, and resolved to cleave to him, when others fastened on hard sayings, and forsook him. Christ's doctrine is the word of eternal life, therefore we must live and die by it. If we forsake Christ, we forsake our own mercies. They believed that this Jesus was the Messiah promised to their fathers, the Son of the living God. When we are tempted to backslide or turn away, it is good to remember first principles, and to keep to them. And let us ever remember our Lord's searching question; Shall we go away and forsake our Redeemer? To whom can we go? He alone can give salvation by the forgiveness of sins. And this alone brings confidence, comfort, and joy, and bids fear and despondency flee away. It gains the only solid happiness in this world, and opens a way to the happiness of the next.

From that time, &c.--or, in consequence of this. Those last words of our Lord seemed to have given them the finishing stroke--they could not stand it any longer.
walked no more--Many a journey, it may be, they had taken with Him, but now they gave Him up finally!

Many of his disciples went back. They stumbled over the remarkable declarations of this chapter. They had no genuine faith.

From this time many of his disciples went back - So our Lord now began to purge his floor: the proud and careless were driven away, and those remained who were meet for the Master's use.