John Calvin Commentary Isaiah 7:9

"and the head of Ephraim is Samaria, and the head of Samaria is Remaliah`s son. If ye will not believe, surely ye shall not be established." — Isaiah 7:9 (ASV)

Meanwhile the head of Ephraim is Samaria. As this is a repetition by which he confirms what he previously said—that God had set boundaries for the kingdom of Israel for an appointed time—I have translated the connective ו, (vau), as meanwhile. Otherwise, it would have been absurd to say that the capital of the kingdom would be preserved after the kingdom had been destroyed, as he recently foretold. The meaning, therefore, is: “In the meantime, until the sixty-five years are fulfilled, Israel enjoys a kind of truce. Its head shall be Samaria. Let Israel be satisfied with its boundaries, and not aim at anything beyond them; for such shall be its condition, until it is utterly destroyed, and is no longer considered to be a people.”

If you do not believe. The particle כי (ki) is placed in the middle of the sentence to indicate the reason or cause; and, therefore, some translate it: “If you do not believe, the reason is that you are not believers.” They limit the former clause to the prophecy of Isaiah but extend the latter to any part of the word of God, as if he had said, “If you have no faith in my sayings, this gives a general proof of your unbelief.” But in that way, the verb תאמינו, (thaaminu), which is in the Hiphil conjugation, will not differ from the verb תאמנו, (theamenu), which is in the Niphal. It is not without reason, however, that the Prophet has changed the termination; and, from many passages of Scripture, it is abundantly evident that the Hebrew verb אמן, (aman), in the Niphal conjugation, signifies to stand, or, to remain fixed in its condition. I interpret it, therefore, as if he had said: “This is the only support on which you can rely. Wait calmly and without anxiety for what the Lord has promised, that is, deliverance. If you do not wait for it, what else remains for you but destruction?”

The particle כי, (ki), therefore, as in many other instances, means truly; for he declares that they cannot stand if they do not rely on the promise. And indirectly he expresses still more: that God will stand, though they disbelieve His word and, as far as it is in their power, endeavor to destroy its stability; but that they will not stand unless they rely on the promise which has been made to them.

From this we should draw a universal doctrine: that when we have departed from the word of God, though we may suppose that we are firmly established, still ruin is near. For our salvation is inseparably linked to the word of God, and when this is rejected, the insult offered to it is justly punished by Him who was ready to uphold people by His power, if they had not by their own choice rushed headlong to ruin. The consequence is that either we must believe the promises of God, or it is futile for us to expect salvation.