What does Obadiah 1:18 mean?

Several centuries before Obadiah gave his warning, the people of Israel split into two separate nations. This occurred just after the rule of Solomon. Ten tribes followed Jeroboam and became the "northern kingdom," sometimes referred to as Ephraim. The other two tribes became the "southern kingdom," also known as Judah. Verse 18 speak of the houses of Jacob and Joseph as references to the northern Kingdom and the southern Kingdom, respectively. Part of Israel's eventual redemption will be unification.

The complete and total destruction of Edom is given vivid imagery. Fire burns through tiny bits of wood and grass very quickly, and leaves virtually nothing behind. As verse 16 noted, nations who oppose God will one day be obliterated, as if they had never existed.

The house of Esau is the nation of Edom. Jacob and Esau were brothers; Jacob's children became Israel while Esau's children became Edom. The nation of Edom was effectively wiped out by Rome in AD 70. This verse seems to suggest that it is not only the nation of Edom, but the very descendants of Esau who will one day be wiped out. This is stated in solemn, sure terms, as something spoken directly by God.