Amos' announcement of Israel's coming judgment came in three waves (vv. 11, 12, and 13-15).
3:11 Sovereign Yahweh announced that an enemy that would surround the land of Israel would destroy and loot its impressive fortresses. That enemy proved to be Assyria, which besieged and destroyed Samaria and overran all Israel in 722 B.C.
3:12 Yahweh also predicted that only a small remnant of the people would survive. The situation would be similar to when a shepherd snatched a remaining fragment of a sheep, a couple of leg bones or a small piece of an ear, from the mouth of an attacking wild animal. It would be like when someone stole everything in a house and the owner could only hold onto a piece of his bed or a bedspread. Similarly an overpowering enemy would steal away the people of Samaria, and only a few would escape.
The figure of a shepherd represented Yahweh in Israel's literature (e.g., Ps. 23:1; et al.). The people would have seen Him as the one who would rescue the remnant as well as the one who would allow the enemy to overpower them.
3:13 Sovereign Yahweh almighty, the suzerain warrior who led the most vast and powerful of all armies, urged Amos to hear His word and to bear testimony against the house of Jacob. The reference to Jacob recalls the devious nature of this ancestor whose character the present generation of Israelites manifested. It also recalls God's gracious promises to Jacob. The Israelites, as bad as they were, were God's people, not just the people of King Jeroboam.
3:14 God now promised to destroy the pagan altars that Jeroboam I had erected at Bethel at the same time He destroyed the people of Israel (cf. 1 Kings 12:26-30). This altar, and the one in Dan, had taken the place of the one in Jerusalem for most of the Israelites. The one in Bethel was the most popular religious center in Israel. There the Israelites practiced apostate worship. The horns of this altar, symbolic of the strength of its deity, would be cut off and would fall to the ground showing its impotence. The horns of an altar were also places of asylum in the ancient Near East (1 Kings 1:50), so their cutting off pictures no asylum for the Israelites when God's judgment came.
3:15 God also promised to destroy the Israelites' winter and summer homes. The fact that many Israelite families could afford two houses and yet were oppressing their poorer brethren proved that they lived in selfish luxury. They had embellished their great houses with expensive ivory decorations (cf. 1 Kings. 21:1, 18; 22:39; Ps. 45:8). The two great sins of the Israelites, false religion (v. 14) and misuse of wealth and power (v. 15), would be the objects of God's judgment.
"The enduring principle here is that God will destroy elaborate altars, expensive houses, and other accoutrements of an extravagant lifestyle when these items are acquired through oppression, fraud, and strong-arm tactics. The idolatry of the people led to their opulent lifestyles. Life apart from God may yield temporary material gain, but it will surely result in eternal loss."41