The book of Isaiah is best understood through its characters. The key players in its saga loom large: the LORD, Israel, Isaiah, King Ahaz, King Hezekiah, Assyria, Sennacherib and Babylon.
The whole book functions as a covenant lawsuit. The LORD brings suit against Israel for its infidelity to the covenant he made with the nation in the time of Moses. In chapter one, the prophet calls witnesses and begins leveling accusations against Israel. Isaiah himself functions as the LORD's mouthpiece in the trial.
Isaiah is the court prophet and chronicler in the times of these kings of Judah: Uzziah, Jotham, Ahaz and Hezekiah. Ahaz plays the largest role of the four kings. His unfaithfulness to the LORD centers on the trajectory of his political decisions. The LORD wants Israel to rely solely on His providence, but Ahaz seeks foreign alliances. This is where a few other key characters sneak into the story. Assyria was the dominant political power in the Near East in the 8th century BC. Since Assyria's dominance threatened surrounding nations, Syria and Ephraim (Ephraim is the name for the ten northern tribes of Israel.) decide to make an alliance and they threaten to take over Judah. Ahaz is afraid, but Isaiah prophesies that he should remain calm and trust in the LORD (7:7). Instead, Ahaz sends tribute to Assyria calling himself the "servant" and "son" of the king of Assyria (2 Kgs 16:7). Ironically, in 732 BC Assyria does save Judah from Ephraim and Syria by attacking their capitals, Damascus and Samaria (2 Kgs 16:9, 17:6). Yet Ahaz's failure to trust in the LORD draws a sharp rebuke from the prophet and Isaiah prophesies Judah's demise at the hands of the Assyrians.
Now things get sticky. The LORD did not want the alliance, but can't bear to destroy Jerusalem just yet. Assyria under the leadership of Sennacherib sweeps down from the north in 701 BC and destroys all the towns of Judah except Jerusalem while Hezekiah is king of Judah. By the LORD's miraculous intervention, Jerusalem is saved, handing a defeat to the mighty Assyrians (37:36). Sennacherib even gets assassinated by his own sons. Yet the LORD is still displeased with Israel's unfaithfulness.
Hezekiah blunders by showing the envoys of the king of Babylon all his treasure. They had sought political alliance with Judah, but after seeing the treasure, opt for conquest of Judah instead. Isaiah gives an ominous prophecy of impending doom to Hezekiah for his foolish ostentation (39:5-7). Later on (605 BC), Babylon does conquer Judah and takes the Jews as captive slaves.
So, how does the contemporary reader learn from Isaiah? Two simple lessons come to mind. First, God fulfills his word. In Isaiah, the LORD foretells many events and they come to pass. Through Isaiah, the LORD speaks of destruction and judgment, but also of salvation and redemption. On all counts, he delivers. Therefore, we can trust in his word for he is always faithful. Second, God's plan incorporates all mankind. Many times in the book of Isaiah, the prophet speaks of a jubilant day when all nations will come to worship the LORD at Jerusalem, on Mt. Zion (cf. 25, 66). This awesome day of feasting and celebration is the goal toward which all history tends. In the end, God wins and we share in his victory. From a Christian perspective, this goal is won by the death and resurrection of Jesus Christ, the true son of David and root of Jesse (11:1).
Isaiah's prophecies are so important for the NT that some of the church fathers referred to him as the first evangelist. The key passages regarding Jesus are about the virgin birth (7:14), the coming of Immanuel (9:1-7), the sprouting of the root of Jesse (11), the suffering servant (53-55) and the mission of the Messiah (61).
By Mark Giszczak