John Calvin Commentary Isaiah 36:15

"neither let Hezekiah make you trust in Jehovah, saying, Jehovah will surely deliver us; this city shall not be given into the hand of the king of Assyria." — Isaiah 36:15 (ASV)

And let not Hezekiah make you trust in Jehovah. He quotes the exhortation by which Hezekiah encouraged the people and speaks lightly of it as an idle and unfounded speech. Thus we see plainly that wicked men, though they assert the power of God, treat it with contempt; for although he does not openly deny that God can assist, if he chooses, yet, by sapping the foundations of their faith, he does all that he can to reduce the power of God to nothing. His intention is to discourage the hearts of the people in such a manner that they might be constrained, as if in despair, to submit and receive laws from a victorious tyrant.

But in order to destroy their confidence in the assistance of God, he also employs another expedient: flattering their hearts with the allurements of a more comfortable life. For there is nothing to which we are more prone than to revolt from God when we are drawn away by the appearance of advantage.

If the world flatters and caresses, the hope of eternal salvation quickly passes away; for our senses are always fixed on the present state of things. Fortified by this resource, Rabshakeh advises, “Do not depend on an uncertain hope, but rather receive what is certain.” And this discourse is powerfully suited to persuade; for nothing is more agreeable to people than to have in hand what they consider desirable; and they are so impatient of delay that they prefer an immediate advantage to what is very distant.

Rabshakeh, therefore, reasons as follows: “Hezekiah promises you the assistance of God, but we do not see it; he holds you in suspense about what is uncertain; but my king promises you those things that are at hand and will assuredly bestow them.” This might appear to be a strong argument; but we must observe the sophistry, for by the same stratagem does Satan frequently attack us and lead us away from confidence in God.

The Lord calls us to the hope of eternal life. That hope is concealed, for we hope for what we do not see (Romans 8:25). He promises that he will be our deliverer, and yet he allows us to languish and pine. As a result, it appears that our hope is vain if we look at the present condition of things.

On this ground Satan attacks us. “Why do you hope in vain? What is the fruit of your faith? What do you expect beyond the world?” In short, this is our daily lamentation.

When Christ calls us to heaven, Satan endeavors to keep us still on the earth. Therefore, we must adhere firmly to the promises so that, hoping against hope (Romans 4:18), we may trust in God and not suffer ourselves to be drawn away from him by any allurements.