John Calvin Commentary Isaiah 8:15

"And many shall stumble thereon, and fall, and be broken, and be snared, and be taken." — Isaiah 8:15 (ASV)

And many among them shall stumble. He goes on to threaten the ungodly, as he had previously begun, and declares that those who refuse to trust in God will not escape without being punished. The threatening runs as follows: “when they have stumbled, they will then fall, and afterwards they will be bruised.” This agrees with the former metaphor, in which he compared God to a stone. Christ has alluded to that metaphor, including both clauses.

He who shall fall on this stone will be broken; but on whomsoever it shall fall, it will bruise him. (Matthew 21:44)

And shall be snared and taken. This agrees with the latter metaphor, in which he compared God to a snare and trap. Let the ungodly, therefore, not imagine that they are stronger or wiser than God, for they will find that he excels them in strength and wisdom, and that to their destruction. They must, therefore, unavoidably be ruined, for either they will be utterly bruised, or they will be snared in such a manner that they can never extricate themselves.

This threatening also concerns the godly, so that they might not hesitate to withdraw from holding fellowship with the multitude and might not resolutely disregard the sinfulness of revolt. Now, this does not strictly belong to God, but is rather, as we would say, accidental; for it is proper to God to receive people into his favor and to give them a firm security for their salvation. That was more clearly manifested in Christ and is still manifested; and therefore, Peter reminds us that though many unbelievers stumble, this is no reason why their stumbling should obstruct the progress of our faith, for Christ is nevertheless a chosen and precious stone. (1 Peter 2:4)