While being the shortest book in the Old Testament I still find Obadiah has a lot to teach us, and the short length means we get to cover a lot of topics in short time.
The book is about God’s judgement, first on Edom, for their sin against Israel, and then on all nations. We see God’s judgement is just for the wrongdoing of Edom deserves punishment, and God is gracious for He will restore and bless Israel to fulfill His plan.
We can divide the book into 3 sections, starting with v1-9:
 The vision of Obadiah. Thus says the Lord GOD concerning Edom: We have heard a report from the LORD, and a messenger has been sent among the nations: “Rise up! Let us rise against her for battle!”
 Behold, I will make you small among the nations; you shall be utterly despised.  The pride of your heart has deceived you, you who live in the clefts of the rock, in your lofty dwelling, who say in your heart, “Who will bring me down to the ground?”  Though you soar aloft like the eagle, though your nest is set among the stars, from there I will bring you down, declares the LORD.
 If thieves came to you, if plunderers came by night— how you have been destroyed!— would they not steal only enough for themselves? If grape gatherers came to you, would they not leave gleanings?  How Esau has been pillaged, his treasures sought out!  All your allies have driven you to your border; those at peace with you have deceived you; they have prevailed against you; those who eat your bread have set a trap beneath you— you have no understanding.  Will I not on that day, declares the LORD, destroy the wise men out of Edom, and understanding out of Mount Esau?  And your mighty men shall be dismayed, O Teman, so that every man from Mount Esau will be cut off by slaughter.
The book starts off telling us that Edom will face a terrible destruction. The first reason for this is Edom’s pride (v3) which means they think they are safe because of the mountains in which they live. They also found safety and confidence from their allies (v7), their wisdom (v8) and their strength (v9).
Even if these things would put them beyond man’s reach, they aren’t out of God’s reach (v4). Their destruction will be terrible and thorough as we see in v5 and v6. Their allies, who they must have found comfort in, will even turn against them (v7)
What things do we find our security in, instead of recognising God’s sovereignty? Is it the place I live, my job, my friends, my family? While these are all great gifts of God let’s be reminded not to prize them for themselves. Let’s remember God has more power than anything on earth.
In the next section we then learn why God wants to destroy Edom:
 Because of the violence done to your brother Jacob, shame shall cover you, and you shall be cut off forever.  On the day that you stood aloof, on the day that strangers carried off his wealth and foreigners entered his gates and cast lots for Jerusalem, you were like one of them.  But do not gloat over the day of your brother in the day of his misfortune; do not rejoice over the people of Judah in the day of their ruin; do not boast in the day of distress.  Do not enter the gate of my people in the day of their calamity; do not gloat over his disaster in the day of his calamity; do not loot his wealth in the day of his calamity.  Do not stand at the crossroads to cut off his fugitives; do not hand over his survivors in the day of distress.
It is because they have turned against their brother Jacob, ie Israel, in a time of distress that they deserve this punishment.
Some of what they did was passive, for example in v11 they stood aloof, and some was active, for example in v14 they handed over survivors. They clearly also gloated and enjoyed Israel’s distress (v12, 13). They are condemned for being like the other foreigners (11), when they should have been Israel’s brother.
A couple of more themes are raised here and will be picked up again below, as the message expands from Edom to all nations:
 For the day of the LORD is near upon all the nations. As you have done, it shall be done to you; your deeds shall return on your own head.  For as you have drunk on my holy mountain, so all the nations shall drink continually; they shall drink and swallow, and shall be as though they had never been.  But in Mount Zion there shall be those who escape, and it shall be holy, and the house of Jacob shall possess their own possessions.  The house of Jacob shall be a fire, and 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 for the house of Esau, for the LORD has spoken. The Kingdom of the LORD
 Those of the Negeb shall possess Mount Esau, and those of the Shephelah shall possess the land of the Philistines; they shall possess the land of Ephraim and the land of Samaria, and Benjamin shall possess Gilead.  The exiles of this host of the people of Israel shall possess the land of the Canaanites as far as Zarephath, and the exiles of Jerusalem who are in Sepharad shall possess the cities of the Negeb.  Saviors shall go up to Mount Zion to rule Mount Esau, and the kingdom shall be the LORD’s.
This section takes us beyond Edom, to the judgement of all nations, and the restoration of Israel. Before looking in detail at this section, let’s first look at a couple of themes that have been running through the whole book.
We see the repeating word “day” continuing in this section. We first saw it used in v8, about the day of Edom’s destruction,then dramatically in v11-14 about the day of Jacob’s distress and now to take us to the day of judgement for all nations, v15. And so I think we should take from this book to remember that the “the day of the Lord is near upon all the nations”.
We have also seen a correspondence between the crime and the punishment, for example v6 told us that Esau would be pillaged, and then in v11 we see it is because of their part in the pillaging of Israel; in v3 we see the pride of Edom, which God would humble in v2. . In v14 Edom handed over Israel’s survivors, but Edom will have no survivors (v18).
Looking now at the above passage, in v15-16 we see that the judgement coming to Edom is something that will similarly come to all nations, and worse, for they will continually drink this punishment. We also see this punishment on Edom will come from Israel, from the fire of Jacob and the flame of Joseph.
17 and v19-21 then show us the restoration of Israel, that their land will increase, and they will rule as God’s kingdom, including ruling over Edom’s land.
While a partial restoration for Israel came under Ezra’s rebuilding of the temple, and later the land was increased under the Maccabees I think we can also think of this restoration as being after the day of judgement of all nations, given the context of v15-16, and other similar passages elsewhere in the bible. And so, we should take this reminder that judgement will come upon all of us, and be thankful for our salvation through Jesus, that we be spared our due punishment and can instead look forward to an eternity in God’s kingdom.