The first 5 chapters of Isaiah outline his prophecies, but do not establish his calling. In chapter 6 we read the details of God’s calling for Isaiah.
In many ways, Isaiah filled a role least desired among men. He was a messenger during a time when the message was not positive. God’s judgment was building with Judah and it was Isaiah’s duty to confront them with truth. Confrontation is never easy. In fact, it’s awful! However, Isaiah’s heart broke for the people. He grieved in the same way the Lord did. He didn’t relay the message in a condescending way, but rather, from a position of love. Repentance and restoration dogged Isaiah’s mind.
Isaiah’s name means, “the Lord saves.” This was another role for him. He would bring a message of hope to a nation that longed for a Messiah. Even his son’s names (Isaiah 7 &8), would point to King Jesus. So, alongside the judgment and truth is the message of hope and Salvation. It is the message of grace and truth.
Some theologians call the book of Isaiah “remnant theology.” Essentially, the judgment of the wicked and the salvation of the faithful remnant. It’s ironic to consider that the same man (Isaiah) who condemned Judah also foreknew their great victory through Christ. What I appreciate most about Isaiah is the continual reliance he places upon the Lord in all circumstances. He counted human wisdom as rubbish compared to God’s sovereignty. In order to fulfill his purpose, he had to!