The Catholic theologian Gerald O’Collins, S.J., has called the writings of the prophet Isaiah “the fifth gospel.” By this he means that so many of the themes of the gospels, enfleshed in their portrayal of Jesus, have their scriptural beginnings in Isaiah. Isaiah’s connection to the story of Jesus seems particularly strong in the Advent and Christmas seasons. Even the prophet’s name — Isaiah means “Yahweh saves” — foretells the Christmas story.

The book of Isaiah is one of the longest books in the Old Testament and the writings within it were composed over a period of so many years that most scholars believe there were at least three “prophet Isaiahs.” That is, prophets who lived long after the original Isaiah attached themselves to his name and style because of his importance and effectiveness as a conveyer of God’s message. For that reason the portions of the book of Isaiah between chapters 40 and 55 are often called “Deutero” or second Isaiah, and the chapters from 56 to 66 are called “Trito” or third Isaiah.

During the time of Jesus, nearly 800 years after the prophet’s own life and death, the words of Isaiah continued to be read prominently in the synagogue. Jesus probably heard more about what Isaiah had to say than about any other prophet. In the gospel of Luke, Jesus begins his ministry by reading a passage from the prophet Isaiah and applying the message to his own ministry (Luke 4:16-21).

In the earlier chapters of Isaiah, the prophet gives us quite a bit of information about himself. His father’s name was Amos and he was a lifelong resident of the city of Jerusalem. His concerns are those of the city, the king, and the Temple. Isaiah was called to prophetic service in the year King Uzziah of Judah died, which would have been around 742 B.C. He appears to have been around 18 years old at the time. He was married to a woman who was herself a prophetess (there were many more men and women prophets in those times than those whose writings have survived in Scripture). He had two sons. Isaiah preached at a critical time in the history of the Jewish people. The original nation of Israel had divided into two, Israel to the North and Judah to the South. Each had its own king, and they were constantly in conflict with each other and with larger, more powerful nations. Isaiah tried to advise three successive kings of Judah (Jotham, Ahaz and Hezekiah) who sometimes accepted his counsel but more often ignored him to follow their own priorities. Isaiah disappeared from the scene sometime around 701 B.C.

The writings of Isaiah are distinguished among the Old Testament writings for their extraordinary literary quality. Isaiah was a poet who used vivid and powerful images and symbols to convey his message. He manages to preach even uncomfortable messages in a style that makes them possible to digest.

Isaiah’s writings are prominent in the liturgies of Christmas for these reasons:

1. He is a prophet of hope and new beginnings. In particular, he speaks of the birth of a new king who will be a “Wonderful Counselor” and “Prince of Peace.” Isaiah’s own prophetic eye may have looked no further than the birth of Ahaz’s son Hezekiah, who did turn out to be one of the better (though by no means perfect) kings of Judah. But Christians have seen in his words a foretelling of the birth of Jesus.

2. He is a prophet of the compassion of God. Isaiah’s God is a God of mercy, comfort and consolation, much like the Father of whom Jesus spoke.

3. Isaiah was the first to articulate that the God of the Jews is also the God of all people. God’s mercy was to reach beyond the boundaries of Jerusalem and Judah to extend to all peoples in every corner of the earth. Jesus, who brought the gospel to Jew and Gentile alike, very consciously exercised his ministry in the spirit of Isaiah.

4. Isaiah is a prophet of peace and justice. Harmony among all peoples and compassion for the poor are the hallmarks of God’s presence. In these matters Jesus spoke out of a prophetic tradition that truly began with Isaiah.