Isaiah lived in the southern kingdom of Judah and witnessed the collapse of the northern kingdom of Israel under the Assyrian onslaught, and attributed it to their sustained rebellion against God. Judah would have fallen to Assyria as well had not God intervened and saved them. Isaiah was born into nobility, was married with at least two sons, and was the greatest preacher of his time with a ministry that lasted 40 years.
During this time, Isaiah would interact with four of Judah's kings - Uzziah, Jotham, Ahaz and Hezekiah. He served as God's messenger, and his message was a call to a wayward people to come back to the Lord and to the security of His covenant promises to the faithful. He lived during troubled times, with the constant threat of expansionist and cruel Assyria at the doorstep of Judah.
The Book of Isaiah is referenced at least 66 times in the New Testament (more than any other Old Testament book other than the Psalms), and Jesus quotes the book as He begins His ministry (Luke 4:16-21; Isaiah 61). Isaiah's prophecy of the suffering servant was a prophecy of Jesus. The Book of Isaiah was relevant to the people of his time (even if largely ignored), was a revelation of the mission of God's Son to future generations, and is salient today. If nothing else, we must be reminded that God can turn and be an enemy to an apostate church and to a godless society. This sobering truth is largely ignored and minimized, even by today's evangelical churches and leaders.
God is faithful to His word. He is faithful to the blessings of His word. He is faithful to the judgment mandated by His word. God's ultimate purpose is His own glory, and that glory is best defined in His mercy. A reflective gaze on the cross of His Son is the greatest evidence known to man, as it reveals this great mercy in the midst of this righteous judgment.