Question: "When were Obadiah’s prophecies against Edom fulfilled (Obadiah 1:18-20)?"
Answer: A major factor in determining when Obadiah’s prophecies against Edom were fulfilled rests on when the book was written. The prophet mentions a recent invasion of Jerusalem (1:10-11), which helps to narrow down the date of writing. Jerusalem experienced four different invasions in Old Testament times, yet only two fit the time period under discussion in Obadiah. The early date would be about 841 B.C., when the Philistines and Arabians attacked Jerusalem during the reign of King Jehoram (2 Chronicles 21:16-17). The later date would be approximately 586 B.C., following the invasion of Babylon (2 Kings 24-25).
If the earlier date is correct, Obadiah would be the earliest of the prophetic books in the Old Testament. Those who hold this position refer to 2 Kings 8:20, which mentions Edom setting up its own king: “In his days Edom revolted from the rule of Judah and set up a king of their own.” Also used to support this date are comparisons of 2 Chronicles 21:16-17 with Joel 3:3-6 and Obadiah 1:11-12; as well as similarities between Obadiah 1:1-9 and Jeremiah 49:7-22.
If the later date is correct, the prophecy of Obadiah regarding Edom’s doom is more dramatic. Babylon completed its invasion of Jerusalem under King Nebuchadnezzar in 586 B.C. In the fifth century B.C., a people called the Nabateans defeated the Edomites and forced them from the city of Petra. The interval between prediction and fulfillment would, therefore, have been very short.
Regardless of the exact date, the predictions against Edom have already been fulfilled. Edom was removed from its land in the fifth century B.C., and there are no survivors of Edom today. This fulfilled the prediction in Obadiah 1:18: “They shall burn them and consume them, and there shall be no survivor for the house of Esau.” Some first-century leaders, such as Herod the Great, still traced their ancestry to Edom, but all mention of Edomites fades after the Jewish Wars of that era. At the end of the 4th century, Jerome referenced the land of Idumea (Edom), but the people of the region had long since disappeared.