Wherefore by their fruits, etc. - This truth is often repeated, because our eternal interests depend so much upon it. Not to have good fruit is to have evil: there can be no innocent sterility in the invisible tree of the heart. He that brings forth no fruit, and he that brings forth bad fruit, are both only fit for the fire.

Wherefore by their fruits ye shall know them. This is the conclusion of the whole, and a repetition of what is before said, the more to fix the rule of judgment upon their minds, and engage them to try men by their doctrines, and their doctrines by the standard of the Scriptures, and not believe every spirit; for with some care and diligence such persons may be detected, and the malignant influence of their ministry be prevented. The sum of the whole is, that ordinarily, and generally speaking, as men are, so are the doctrines they preach, and by them they may be known, and judged to be what they are. Christ here, and in the preceding verses, is speaking not of men of bad lives and conversations, who take upon them to teach others; for there is not so much reason to caution good men against these; they are easily detected, and generally discarded; but of men that put on sheep's clothing, who pretended to much holiness of life and conversation, and strictness of religion; and under that disguise delivered out the most corrupt and unwholesome doctrines; which tended greatly to depreciate him and his grace, and to do damage to the souls of men.

Wherefore by their fruits ye shall know them--that is, But the point I now press is not so much the end of such, as the means of detecting them; and this, as already said, is their fruits. The hypocrisy of teachers now leads to a solemn warning against religious hypocrisy in general.