Obadiah, like other prophets, announces a coming judgment day, "the day of the LORD," when Israel's enemies will be judged and Israel herself will be restored. (For similar passages about the Day of the Lord, see Isaiah 13:6; Ezekiel 30:3; Joel 2:1, 11, 31; Amos 5:18, 20.) The basis for judgment will be the deeds of the nations, "As you have done, it shall be done to you; your deeds shall return on your own head." Specifically, because Edom betrayed Judah, Edom itself will be destroyed.
Verse 16 speaks of the Israelites having "drunk" on the holy mountain, and then of the nations "drinking." This verse is best understood in light of Jeremiah 25:15-29, where God gives Jeremiah the "cup of the wine of wrath" and makes all the nations drink from it. Judah has already drunk from the cup of wrath, as evidenced by the Babylonian exile. Now the cup will pass to the other nations.
The final part of the passage holds out hope not only for Judah but also for the long-lost northern kingdom of Israel. The "house of Jacob" (Judah) and the "house of Joseph" (Israel) will be restored and they will consume Edom as fire consumes straw. The prophet's message of judgment and restoration is summarized in these few verses.
15 For the day of the Lord is near against all the nations.
As you have done, it shall be done to you;
your deeds shall return on your own head.
16 For as you have drunk on my holy mountain,
all the nations around you shall drink;
they shall drink and gulp down,*
and shall be as though they had never been.
17 But on Mount Zion there shall be those that escape,
and it shall be holy;
and the house of Jacob shall take possession of those who dispossessed them.
18 The house of Jacob shall be a fire,
the house of Joseph a flame,
and the house of Esau stubble;
they shall burn them and consume them,
and there shall be no survivor of the house of Esau;
for the Lord has spoken.
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org