One of the subtler themes of the book of Amos is this: that God hates strongholds.
That probably requires a little explanation. Chapters 1 and 2 are full of references to these fortified places. There are the strongholds of Ben-hadad in Syria, the stronghold of Gaza in Philistia, the stronghold of Tyre, and so on. Each of seven strongholds mentioned is slated to be devoured by fire, the judgment of God poured out upon them. Then in chapter 3 the word “strongholds” is used four times, and it is Israel’s strongholds, particularly Samaria, which are in view.