Who wrote Isaiah:

The obvious author of Isaiah is the prophet Isaiah who ministered in Judea in the late eighth century B.C. However, like any other accurate prophetic book of the Bible, critical scholars suggest the events foretold in the book of Isaiah must have been recorded after the events. Some scholars point to the changes in writing style, vocabulary, and theology throughout Isaiah as further evidence of a second or even third author.

Below is a breakdown of three different theories regarding the authorship of Isaiah:

The Two Author Theory:

• The writing style, vocabulary, and theology of chapters 1-39 differ from chapters 40-66.
• Chapters 1-39 predict the fall of Jerusalem while chapters 40-66 takes place after the fall of Jerusalem and the end of the exilic period. Those critical of Isaiah’s prophetic abilities suggest Isaiah could not have known the events of the fall of Jerusalem ande events of the post exilic period. Therefore two different authors (referred to as Isaiah and Deutero-Isaiah) must have written the book at different times.

The Three Author Theory:

• Chapters 1-39, 40-55, and 56-66, all speak of different time periods using various writing styles and vocabulary. Those in favor of the Three Author Theory believe this suggests three different authors (referred to as Isaiah, Deutero-Isaiah, and Trito-Isaiah) wrote the book of Isaiah at different times.
• Scholars in favor of the Three Author Theory also agree prophetic abilities are an impossibility. Therefore, the events must have been recorded by someone living at the beginning of the exilic period, someone living at the end of the exilic period, and a third person living after the exilic period.

Single Author Theory:

• Scholars in favor of the Single Author Theory suggest the various writing styles are a reflection of various issues brought up within the book. Chapters 1-39 are critical and judgmental and the author would have used a writing style to reflect appropriate emotions. Chapters 40-66 are hopeful and exciting. A single author would be forced to change the writing style to reflect such emotions.
• The apparent change in theology is only a change in perspective of God. The first perspective found in chapters 1-39 is critical of the nation of Israel. Therefore, the theology will reflect the judgmental qualities of God. When the author speaks of the end of the exilic period the theology focuses on the forgiving and fatherly qualities of God.
• If a Deutero-Isaiah and Trito-Isaiah contributed to the book of Isaiah, they would have done so while living in Babylon. However, the geography and vegetation described remain consistent with Palestine, suggesting anyone who may have contributed to the book of Isaiah lived in Palestine, not Babylon.

Whether or not one personally believes in the prophetic abilities of man or God, this belief cannot factor in as evidence when dating an allegedly prophetic book. The book of Isaiah claims Isaiah possessed prophetic abilities. According to the laws of scientific deduction, one would have to first disprove Isaiah’s claim of being a prophet before using it as evidence of multiple authors.

If one can disprove Isaiah’s prophetic abilities, then one is free to conclude (and must conclude) Isaiah was written after the events. However, until one is able to disprove Isaiah’s claim of being a prophet, his claim of being prophetic must be considered as potentially true.

At no time in history was it ever believed or suspected the book of Isaiah was written by anyone other than the Isaiah of history. Aside from a presumption that no man has ever been warned by God of the future, there is little evidence to support the multiple author theories. Because we cannot use this presumption as evidence, we must conclude Isaiah was probably written by one man; Isaiah.