Obadiah tells of God's harsh judgment against Edom and other ungodly nations. It's a sobering picture that is still relevant today.
The book of Obadiah may be small, but it packs a powerful punch against the arrogance of Edom and other ungodly nations. The Edomites, who were descended from Jacob's brother Esau, still carried the grudge their founder had for Jacob's deception. They refused to help Israel in their need, sold them as slaves, and even abused them while they were exiled to Babylon.
Through Obadiah, God declares judgment over Edom and prophesies that they will be erased from history. Babylon overtook Edom 100 years later, and they never recovered.