3:8 who can but prophesy. Just as a lion’s voice evokes fear, so the voice of the Lord compels the prophets to proclaim His word (Deut. 18:18; cf. 1 Cor. 9:16).
3:8 Two more rhetorical questions complete the group of nine (vv. 3–6). It would do Israel no good to forbid prophecy (2:12; 7:13, 16); the true prophet must prophesy, just as certainly as God’s judgment must come to pass.
The effect God’s warnings should have (3:8)
a. The people should fear (3:8a). Half of the dispute is settled already. The audience knows that the punishment announced in 3:2b is a warning of what God will do. But the dispute for human hearts, which are the object of the dispute, is still to be settled. If there is no positive response to the mind’s understanding of the message, the dispute will fail to cause its intended results. Thus Amos calls for a personal decision of the heart and will. This shift is revealed in the change in style which contrasts a statement of fact (3:7) with a call for a response (3:8). In the process Amos integrates earlier images (3:4–6) and applies them to the present human situation. The hypothetical attack of a lion becomes reality, and the sound of the trumpet warning is heard. God’s word is the warning and God is the lion (1:2). Since he has roared, he must be in the process of attacking his prey (3:4). This roar is like a trumpet blast which warns a city (3:6); this roar is the prophet’s message of judgment that precedes God’s action (3:7). Is it possible that men will not fear? What other results could this warning cause? A response of fear is necessary if the two parties are to walk together in unity again (3:3).
b. The prophet should warn (3:8b). To encourage this response, Amos identifies the source of his message. This message of punishment is what God has spoken. It is impossible for a man to ignore such a warning and not proclaim it. Amos responded in fear and gave this unpopular prophecy. Now he calls on the nation to respond in fear. The context implies (3:6) that this fear is a trembling before the almighty power of God which determines each person’s destiny. In later chapters he will call for a fuller response. At this point Amos is calling on the people to take the first step and accept the fact that God has announced the judgment of Israel.
In the Near Eastern world it was commonly believed that all events were causally related. If Ur was destroyed by an enemy, the gods were angry (ANET, 455); if there was a victory in war, the gods brought it about. Babylonian records indicate that every event was significant. The shape of rising smoke could predict the future, the behavior of wild animals were omens of good or bad fortune, and the appearance of the stars and the shape of the moon affected one’s fate. Israel also looked for and saw cause-and-effect relationships between events. God was not a theological abstraction that had no contact with or power over the history of natural and human events.54
As people gain financial security, social acceptance, status, political independence, and greater pleasure, their need for dependence on God tends to evaporate. Religion can become a dead acceptance of traditions. The maintenance of the social and political status quo can soon replace the theological implications that true faith has. A person’s concept of responsibility before God and neighbor can be perverted because God no longer affects the events of daily life. Although everyone knows that every effect has a cause, the time delay between an act and its effect can deceive some into forgetting this basic law of life.
Tradition taught that Israel was elect (2:10; 3:2). God elected and redeemed his people from Egypt (2:9–10; 3:1), but Amos announced a contrary message of punishment and destruction (2:13–16; 3:2). This paradoxical reaction by God is fundamentally rejected by Amos’ audience because it is contrary to their orthodoxy. This happened because their orthodoxy eliminated the dynamic of a trusting relationship with God and substituted a static non-relational guaranteed benefit based on covenant promises of blessing. In order to persuade his audience, Amos first redefines the rational contact between cause-and-effect in nature. After he applies the cause-and-effect principle to God’s action, he concludes by challenging his audience to allow the cause (God’s roar) to have an effect (fear) in their lives (3:8).
Although theology does not always seem to be logical to the unbeliever, rationality is a part of the process that helps people understand the nature of the relationship between God and the world. Although God may seem to act irrationally in grace to elect a favored people, God does not irrationally inspire a prophet to deliver a message of destruction on his chosen people unless there is a cause. In fact, God limits his activity to a prophet’s prior announcement of his action (3:7). Therefore, even the roar of God through the prophet’s mouth is an act of grace that warns Israel of God’s impending judgment. The cause of Amos’ prophecy is God’s roar. Who knowing God’s word can help but proclaim it (3:8)? Only those who do not fear God. Only those whose deadened orthodoxy has removed God from the relational, cause-and-effect world of reality can dare ignore the roar of the lion.
 Sproul, R. C. (Ed.). (2005). The Reformation Study Bible: English Standard Version (p. 1270). Orlando, FL; Lake Mary, FL: Ligonier Ministries.