(Michael D. Coogan, A Brief Introduction to the Old Testament, 2009, p. 256.)
The book opens with a historical note about the prophet, then a short oracle announcing Yahweh's judgment (repeated in the Book of Joel). The prophet denounces the crimes against humanity committed by the gentile nations, tells Israel that even they have sinned and are guilty of the same crimes, and report five symbolic visions prophesying the destruction of Israel. Included in this, with no apparent order, are an oracle on the nature of prophecy, snippets of hymns, oracles of woe, a third-person prose narrative concerning the prophet, and an oracle promising restoration of the House of David, which had not yet fallen in Amos's lifetime.
Amos prophesied during the reign of Jeroboam II, King of Israel, and of Uzziah of Judah, which places him in the first half of the 8th century BC. According to the book's superscription (Amos 1:1) he was from Tekoa, a town in Judah south of Jerusalem, but his prophetic mission was in the northern kingdom. He is called a "shepherd" and a "dresser of sycamore trees", but the book's literary qualities suggest a man of education rather than a poor farmer.
Scholars have long recognized that Amos utilized an ancient hymn within his prophecy, verses of which are found at 4.13; 5.8–9; 8.8; 9.5–6. This hymn is best understood as praising YHWH for His judgment, demonstrated in His destructive power, rather than praise for creation. Scholarship has also identified 'Sumerian City Lament' (SCL) motifs within Amos and particularly the hymn, offering the possibility that Amos used SCL as a literary template for his prophecy of Jerusalem's destruction. The Amos hymn has also been discussed in terms of a 'covenant curse' which was used to warn Israel of the consequences of breaking the covenant, and in particular a 'Flood covenant-curse' motif, first identified by D.R. Hillers. Recent scholarship has shown Amos' hymn is an ancient narrative text, has identified a new verse at 7.4; and has compared the hymn to the Genesis Flood account and Job 9:5–10.
The central idea of the book of Amos is that God puts his people on the same level as the surrounding nations – God expects the same purity of them all. As it is with all nations that rise up against the kingdom of God, even Israel and Judah will not be exempt from the judgment of God because of their idolatry and unjust ways. The nation that represents YHWH must be made pure of anything or anyone that profanes the name of God. God's name must be exalted.
Amos is the first prophet to use the term "the Day of the Lord. This phrase becomes important within future prophetic and apocalyptic literature. For the people of Israel "the day of the LORD" is the day when God will fight against his and their enemies, and it will be a day of victory for Israel. However, Amos and other prophets include Israel as an enemy of God, as Israel is guilty of injustice toward the innocent, poor, and young women. To Amos "the day of the Lord" will be a day of doom.
Other major ideas in the book of Amos include: social justice and concern for the disadvantaged; the idea that Israel's covenant with God did not exempt them from accountability for sin; God is God of all nations; God is judge of all nations; God is God of moral righteousness; God made all people; God elected Israel and then liberated Israel so that He would be known throughout the world; election by God means that those elected are responsible to live according to the purposes clearly outlined to them in the covenant; if God destroys the unjust, a remnant will remain; and God is free to judge whether to redeem Israel.