Let them alone. He sets them aside as unworthy of notice, and concludes that the offense which they take ought not to give us much uneasiness. Hence has arisen the distinction, of which we hear so much, about avoiding offenses, that we ought to beware of offending the weak, but if any obstinate and malicious person take offense, we ought not to be uneasy; for, if we determined to satisfy all obstinate people, we must bury Christ, who is the stone of offense, (1-Peter 2:8.) Weak persons, who are offended through ignorance, and afterwards return to just views, must be distinguished from haughty and disdainful men who are themselves the authors of offenses. It is of importance to attend to this distinction, in order that no one who is weak may be distressed through our fault. But when wicked men dash themselves through their obstinacy, let us walk on unmoved in the midst of offenses; for he who spares not weak brethren tramples, as it were, under foot those to whom we are commanded to stretch out the hand. It would be idle to attend to others, whom we cannot avoid offending, if we wish to keep the right path; and when, under the pretext of taking offense, they happen to fall off and revolt from Christ, we must let them alone, that they may not drag us along with them. [1] They are blind leaders of the blind. Christ means that all who allow themselves to be driven hither and thither at the disposal of those men will miserably perish; for when they stumble on a plain road, it is evident that they are willfully blind. Why then should any one allow himself to be directed by them, except that he might fall into the same ditch? Now Christ, who has risen upon us as the Sun of righteousness, (Malachi 4:2,) and not only points out the road to us by the torch of his Gospel, but desires that we should keep it before us, justly calls on his disciples to shake off that slothfulness, and not to wander, as it were, in the dark, for the sake of gratifying the blind. [2] Hence also we infer that all who, under the pretense of simplicity or modesty, give themselves up to be deceived or ensnared by errors, are without excuse.

Footnotes

1 - "De peur qu'ils nous tirent en perdition avec eux;" -- "lest they draw us to perdition along with them."

2 - "A bon droict retire ses disciples de ceste nonchalance et stupidite de suyvre les aveugles, et pour leur faire plaisir d'aller tastonnant en tenebres comme eux;" -- "properly withdraws his disciples from that indifference and stupidity in following the blind, and--for the sake of gratifying them--in groping in the dark like them."

Let them alone - That is, do not be troubled at their rage.
Be not anxious about it. This result is to be expected. They are greatly attached to their traditions, and you are not to wonder that they are indignant. They lead, also, the blind. They have a vast influence over the multitude, and it is to be expected that they will be enraged at any doctrines that go to lessen their authority or influence. By commanding them "to let them alone," Christ does not mean that they were to be suffered to remain in error without any attempt to refute or correct them, for this he was doing then; but he meant to charge his disciples not to mind them or to regard their opposition - it was to be expected.
If the blind lead the blind - This was a plain proposition. A blind man, attempting to conduct blind men, would fall into every ditch that was in the way. So with religious teachers. If these Pharisees, themselves ignorant and blind, should be suffered to lead the ignorant multitude, both would be destroyed. This was another reason for confuting their errors, or for rooting up the plants which God had not planted. He wished, by doing it, to save the deluded multitude.
God often suffers one man to lead many to ruin. A rich and profligate man, an infidel, a man of learning, a politician, or a teacher, is allowed to sweep multitudes to ruin. This is not unjust, for those who are led are not compelled to follow such people. They are free in choosing such leaders, and they are answerable for being led to ruin.

Let them alone - Αφετε αυτους, give them up, or leave them. These words have been sadly misunderstood. Some have quoted them to prove that blind and deceitful teachers should not be pointed out to the people, nor the people warned against them; and that men should abide in the communion of a corrupt Church, because that Church had once been the Church of God, and in it they had been brought up; and to prove this they bring Scripture, for, in our present translation, the words are rendered, let them alone: but the whole connection of the place evidently proves that our blessed Lord meant, give them up, have no kind of religious connection with them, and the strong reason for which he immediately adds, because they are blind leaders. This passage does not at all mean that blind leaders should not be pointed out to the people, that they may avoid being deceived by them; for this our Lord does frequently, and warns his disciples, and the people in general, against all such false teachers as the scribes and Pharisees were; and though he bids men do that they heard those say, while they sat in the chair of Moses, yet he certainly meant no more than that they should be observant of the moral law when read to them out of the sacred book: yet neither does he tell them to do all these false teachers said; for he testifies in Matthew 15:6, that they had put such false glosses on the law, that, if followed, would endanger the salvation of their souls. The Codex Bezae, for αφετε αυτους, has αφετε τους τυφλους, give up these blind men. Amen! A literal attention to these words of our Lord produced the Reformation.
Probably the words may be understood as a sort of proverbial expression for - Don't mind them: pay no regard to them. - "They are altogether unworthy of notice."
And if the blind lead the blind - This was so self-evident a case that an apter parallel could not be found - if the blind lead the blind, both must fall into the ditch. Alas, for the blind teachers, who not only destroy their own souls, but those also of their flocks! Like priest, like people. If the minister be ignorant, he cannot teach what he does not know; and the people cannot become wise unto salvation under such a ministry - he is ignorant and wicked, and they are profligate. They who even wish such God speed; are partakers of their evil deeds. But shall not the poor deceived people escape? No: both shall fall into the pit of perdition together; for they should have searched the Scriptures, and not trusted to the ignorant sayings of corrupt men, no matter of what sect or party. He who has the Bible in his hand, or within his reach, and can read it, has no excuse.

Let them alone,.... Have nothing to say, or do with them; do not mind their anger and resentment, their reproaches and reflections, nor trouble yourselves at the offence they have taken; if they will go, let them go; they are a worthless generation of men, who are not to be regarded, hearkened to, nor to be pleased; it matters not what they say of me, and of my doctrine:
they be blind leaders of the blind; the people that hearken to them, and are followers of them, are "blind", as to any true sense of themselves, their state, and condition by nature; as to any spiritual, saving knowledge of God; as to any acquaintance with the Messiah, and the method of salvation by him; as to the Spirit of God, and the work of grace, regeneration, and sanctification upon the soul; as to the Scriptures of truth, and doctrines of the Gospel; and the "leaders" of them were as "blind" as they: by whom are meant the Scribes and Pharisees, the learned doctors and rabbins of the Jewish nation; who thought themselves very wise and knowing, yet they were blind also; and none more than they. It was an old tradition (g) among the Jews,
"that there should be "blind teachers" at the time when God should have his tabernacle among them.''
This was predicted, in Isaiah 42:19 and all such leaders and teachers are blind, who, notwithstanding their natural abilities, and acquired parts, are in a state of unregeneracy; and have nothing more than what they have from nature, or have attained to at school; and as apparently all such are, who lead men from Christ, to mere morality, and to a dependence upon their own righteousness for justification, which was the darling principle of the blind leaders in the text.
And if the blind lead the blind, both shall fall into the ditch; of ignorance and error, immorality and profaneness, distress, if not despair, temporal ruin and destruction; which was notoriously verified in the Jewish people, and their guides: and of eternal damnation, the lake which burns with fire and brimstone; what else can be expected?
(g) Midrash Tillim in Psal. cxlvi apud Grotium in loc.

Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch--Striking expression of the ruinous effects of erroneous teaching!

Let them alone. The Pharisees. His disciples were troubled by their opposition.
They be blind leaders of the blind. They pretend to be spiritual guides of the people, while spiritually blind themselves. The blind are unsafe guides of the blind.

Let them alone - If they are indeed blind leaders of the blind; let them alone: concern not yourselves about them: a plain direction how to behave with regard to all such. Luke 6:39.