The Hebrew word for prophet is nabi (na-BEE), which tranlates to "mouthpiece." The prophets were the mouthpiece of God, trying often to influence a change in the behavior of the Chosen People in much the same way as a parent tries to helpa teen effect positive change.
For example, Amos was a very outspoken prophet. Though a simple shepherd who lived in the southern wilderness, Amos proclaimed his message to the northern kingdom. He used harsh and angry words to warn Israel of its idolatry. He preached at Beth-el, a house of God, where cult worship was taking place, speaking out against the greed of the people and their shabby treatment of the poor. Read Amos 5:15-17. It was Amos who brought new meaning to the phrase "the day of the Lord," referring to a day of darkness not light.
Hosea lived at the same time as Amos. However, he was much less harsh in proclaiming his message. Hosea used a parable to remind Israel of its betrayal of the covenant and of God's faithfulness to them. Read Hosea 1:2. Hosea's marriage to a harlot wife represents Israel's infidelity to God. Hosea combines severe warnings and accusations with promises of forgiveness and hope. If you look at Hosea chapters 2-3, you will find many examples of both warnings and promises of hope.
In spite of the words of these northern prophets, Israel moved closer and closer to judgment day. Because of the division of the kingdom, Israel was no longer able to defend itself properly from outside attacks. In 722 B.C. Israel was conquered by the Assyrians and Judah was made a vassal state of Assyria.
In the southern kingdom, Judah had prophets of its own. Some of the people believed that there was still time to reform their lives and escape destruction. The Book of Isaiah is beleived to record the words of three individual prophets. Chapters 1-39 describe the words of the prophet Isaiah. Isaiah advised Judah's king Hezekiah not to attack Assyria, but rather to rely on God's help to defend the city of Jerusalem. Isaiah used many variations to cajole the people to listen to him. It was only after Isaiah walked through Jerusalem with bare feet and tattered clothes that the king heeded the warning. The results of this warning are included in Isaiah 37:33-37.
Micah uses a similar style to that of Amos with the people of the southern kingdom. His words were much more forceful than Isaiah's. It is believed that King Hezekiah personally repented and reformed his life because of his words, though Micah continued to preach doom for Judah as a whole. Micah speaks on behalf of the poor and oppressed as though he has had personal experience of this way of life. Look at Micah 1:8-9. Later, however, Micah combines his harsh words with words of hope for the restoration of the people. Read Micah 4:1-7.
Though Assyria had destroyed the northern kingdom, Judah was able to remain relatively unaffected for many years because of Assyria's preoccupation with defending itself against its northern enemies. Around 630 B.C., Judah even gained a brief period of independence. It was during this time that the prophet Jeremiah lived. In 626 B.C., Babylon became independent from Assyria. The Babylonians were becoming stronger as Assyria weakened. When the Assyrian nation fell, Babylon and Egypt fought over Judah. First the Egyptians ruled Judah, then King Nebuchadnezzar of Babylon fought both Egypt and Judah. The final battle destroyed Jerusalem in 587 B.C. Solomon's Temple was wiped out. The people were taken to Babylon in exile. God's chosen people had reached rock bottom.