John Calvin Commentary Colossians 2:4

"This I say, that no one may delude you with persuasiveness of speech." — Colossians 2:4 (ASV)

This I say, that no man may deceive you. Since human contrivances (as we will see later) have an appearance of wisdom, the minds of the godly ought to be filled with this conviction: that the knowledge of Christ is in itself amply sufficient. And, unquestionably, this is the key that can close the door against all vile errors.

For what is the reason people have involved themselves in so many wicked opinions, in so many idolatries, in so many foolish speculations, if not this: that, despising the simplicity of the gospel, they have ventured to aspire higher? Accordingly, all the errors in Popery must be considered as proceeding from this ingratitude: that, not being satisfied with Christ alone, they have given themselves over to strange doctrines.

Therefore, the Apostle acts fittingly in writing to the Hebrews. For when he wishes to exhort believers not to allow themselves to be led astray by strange or new doctrines, he first of all makes use of this foundation:

Christ yesterday, and today, and forever. (Hebrews 13:8)

By this he means that those who remain in Christ are out of danger, but those who are not satisfied with Christ are exposed to all fallacies and deceptions. So Paul here would have everyone who does not want to be deceived be fortified by this principle: that a Christian should know nothing except Christ.

Whatever is brought forward after this, no matter how imposing its appearance, will nevertheless be of no value. In short, there will be no persuasiveness of speech that can turn aside, even by a finger's breadth, the minds of those who have devoted their understanding to Christ.

This is certainly a passage that ought to be highly esteemed. For just as he who has taught people to know nothing except Christ has provided a safeguard against all wicked doctrines, so for the same reason we should today destroy the whole of Popery, which, it is manifest, is built on ignorance of Christ.