John Calvin Commentary Obadiah 1:18

"And the house of Jacob shall be a fire, and the house of Joseph a flame, and the house of Esau for stubble, and they shall burn among them, and devour them; and there shall not be any remaining to the house of Esau; for Jehovah hath spoken it." — Obadiah 1:18 (ASV)

Here again the Prophet addresses a doubt that might enter the mind of each of them.

For the Idumeans were flourishing, and their condition was independent, when the Israelites, as well as the Jews, were led into exile, and Jerusalem with its temple was destroyed. Under such circumstances, they might despair.

But the Prophet shows that, though for a time the house of Jacob seemed to be dead, yet a fire would be kindled that would consume the Idumeans. This would happen even though the Idumeans were then proud of their power and wealth, and also of the prosperous outcome of their victory over the Jews, for they, as well as the Assyrians, had been enriched by the overthrow of their brethren.

Isaiah also adopts a similar way of speaking. Though he directs his discourse not to the Idumeans but to others, his manner of speaking is the same when he says that God, the light of Israel, would be a fire and a flame to consume the wicked (Isaiah 29:6).

But this was fulfilled when the Lord avenged the cruelty of Edom. This happened even though the Jews were then in exile and could not move a finger, being without arms, indeed, when they were miserable slaves. Even then, the Idumeans were consumed. By what fire? How was this burning kindled?

Even then the house of Jacob and the house of Joseph were like a fire and a flame. The cause of this ruin, it is true, did not immediately appear to the Idumeans; but we must look here to the purpose of God. Why did God punish the Idumeans with such severity?

Because he intended by this example to show how much he loved his Church. Since, then, their cruelty was the cause of ruin to the Idumeans, the prophet rightly says that the house of Jacob and the house of Joseph would be like a fire and a flame to consume the Idumeans.

And it was not a small solace to the miserable exiles when they understood that they were still regarded by God in their depressed condition. Since, then, they were exposed to the reproach and ridicule of all, it pleased God to testify that they were the objects of his care, and that he would, for their sake, destroy whole nations—even those who then gloried in their power.

We now see, then, why the Prophet adopted this figurative language. By 'the house of Joseph,' he means, as we have said elsewhere, the kingdom of Israel; he mentions a part for the whole.