James 1:26

If any man among you seem to be religious - Pious, or devout. That is, if he does not restrain his tongue, his other evidences of religion are worthless. A man may undoubtedly have many things in his character which seem to be evidences of the existence of religion in his heart, and yet there may be some one thing that shall show that all those evidences are false. Religion is designed to produce an effect on our whole conduct; and if there is any one thing in reference to which it does not bring us under its control, that one thing may show that all other appearances of piety are worthless.

And bridleth not his tongue - Restrains or curbs it not, as a horse is restrained with a bridle. There may have been some reason why the apostle referred to this particular sin which is now unknown to us; or he may perhaps have intended to select this as a specimen to illustrate this idea, that if there is any one evil propensity which religion does not control, or if there is any one thing in respect to which its influence is not felt, whatever other evidences of piety there may be, this will demonstrate that all those appearances of religion are vain. For religion is designed to bring the whole man under control, and to subdue every faculty of the body and mind to its demands. If the tongue is not restrained, or if there is any unsubdued propensity to sin whatever, it proves that there is no true religion.

But deceiveth his own heart - Implying that he does deceive his heart by supposing that any evidence can prove that he is under the influence of religion if his tongue is unrestrained. Whatever love, or zeal, or orthodoxy, or gift in preaching or in prayer he may have, this one evil propensity will neutralize it all, and show that there is no true religion at heart.

This man’s religion is vain - As all religion must be which does not control all the faculties of the body and the mind. The truths, then, which are taught in this verse are:

(1) That there may be evidences of piety which seem to be very plausible or clear, but which in themselves do not prove that there is any true religion. There may be much zeal, as in the case of the Pharisees; there may be much apparent love of Christians, or much outward benevolence; there may be an uncommon gift in prayer; there may be much self-denial, as among those who withdraw from the world in monasteries or nunneries; or there may have been deep conviction for sin, and much joy at the time of the supposed conversion, and still there be no true religion. Each and all of these things may exist in the heart where there is no true religion.

(2) A single unsubdued sinful propensity neutralizes all these things, and shows that there is no true religion. If the tongue is not subdued; if any sin is indulged, it will show that the seat of the evil has not been reached, and that the soul, as such, has never been brought into subjection to the law of God. For the very essence of all the sin that there was in the soul may have been concentrated on that one propensity. Everything else which may be manifested may be accounted for on the supposition that there is no religion; this cannot be accounted for on the supposition that there is any.