Why was Isaiah so important?

Isaiah was a prophet in the Southern Kingdom of Judah. He began his ministry about 740 B.C., several years before the people in the Northern Kingdom of Israel were carried away captive by the Assyrians. He died about 701 B.C., approximately 100 years before Lehi left Jerusalem.

Through Isaiah, the Lord spoke of the apostate condition of the inhabitants of Judah and invited the people to repent and become clean. Isaiah prophesied that the house of the Lord would be established in the last days in the tops of the mountains and that the proud would be humbled at the Savior’s Second Coming.

Isaiah also prophesied of consequences that those in Judah and Jerusalem would suffer for their corruption. He taught that Jerusalem would be restored after it was purged, and he prophesied of events in the last days.

Taken from the Old Testament Study Guide for Home-Study Seminary Students (2014)