Meaning Hebrew "the Lord is salvation."
Figure Major prophet of the eighth century BC; book of Isaiah.
Feast day May 9 (Orthodox); July 6 (Catholic, with all the Old Testament prophets)
Traditions CATHOLICORTHODOXANGLICANPROTESTANT
In the Christian tradition
Isaiah is the major prophet whose name and book contain the Old Testament texts most quoted in the New Testament. The passages on the Suffering Servant (Isaiah 52-53), the Emmanuel prophecy (Isaiah 7:14), and the calling of Isaiah (Isaiah 6) are foundational Christian readings.
The book of Isaiah, traditionally read as the work of the eighth-century BC prophet (with later sections in chapters 40-66 attributed by modern scholarship to one or more successors writing during and after the exile), is the most quoted Old Testament book in the New Testament. Christian liturgy across the traditions draws heavily from Isaiah, particularly in Advent. The figure himself is honored in the Catholic and Orthodox calendars; the Sunday of the Forefathers in Orthodox practice commemorates him alongside other Old Testament figures. The name has come back into significant modern Christian use, particularly in English-speaking Protestant and Evangelical families in recent decades.