John Calvin Commentary James 1:26

"If any man thinketh himself to be religious, while he bridleth not his tongue but deceiveth his heart, this man`s religion is vain." — James 1:26 (ASV)

Seem to be religious. He now reproves a vice even in those who boasted that they were doers of the law—a vice to which hypocrites are commonly prone: namely, the unbridled use of the tongue for slander. He has previously touched on the duty of restraining the tongue, but for a different purpose; for he then instructed silence before God, so that we might be better equipped to learn. He now speaks of another matter: that the faithful should not use their tongue for evil speaking.

It was indeed necessary that this vice should be condemned when the subject was the keeping of the law, because those who have forsaken the more obvious vices are especially prone to this failing. Someone who is neither an adulterer, nor a thief, nor a drunkard, but, on the contrary, appears distinguished by some outward show of holiness, will try to elevate himself by defaming others. This is done under the pretext of zeal, but really stems from the lust of slandering.

The purpose here, then, was to distinguish between the true worshippers of God and hypocrites, who are so swollen with Pharisaic pride that they seek praise from the defects of others. If anyone, he says, seems to be religious,—that is, someone who has a show of holiness and meanwhile flatters himself by speaking evil of others—it is therefore evident that he does not truly serve God. For by saying that his religion is vain, he not only implies that other virtues are marred by the stain of evil-speaking, but also that the conclusion is that the apparent zeal for religion is not sincere.

But deceives his own heart. I do not approve of Erasmus’s translation—“But suffers his heart to err”—for James points out the source of that arrogance to which hypocrites are addicted. Through this arrogance, being blinded by an excessive love of themselves, they believe themselves to be far better than they really are. And from this, no doubt, comes the disease of slandering, because, as Aesop says in his fable, the wallet hanging behind is not seen.

Rightly, then, has James, wishing to remove the effect (that is, the lust of evil-speaking), added the cause: namely, that hypocrites flatter themselves immoderately. For they would be ready to forgive if they, in turn, acknowledged their own need for forgiveness. Therefore, the flatteries by which they deceive themselves about their own vices make them such supercilious censors of others.