
Christianity is a global religion centered on the life and teachings of Jesus Christ, who followers believe is the Son of God. It's a monotheistic faith, meaning Christians believe in one God who exists in three co-equal persons: God the Father, God the Son (Jesus Christ), and the Holy Spirit. Christianity is based on the Bible, with the Old Testament and New Testament serving as sacred texts.

The Christian doctrine of the Trinity (Latin: trinus "threefold") holds that God is one God, but three coeternal consubstantial persons or hypostases. These being the Father, the Son (Jesus Christ), and the Holy Spirit - as "one God in three Divine Persons". The three Persons are distinct, yet are one "substance, essence or nature" (homoousios).

Book of Isaiah, or Isaiah is the first of the Latter Prophets in the Hebrew Bible and the first of the Major Prophets in the Christian Old Testament. It is identified by a superscription as the words of the 8th-century BCE prophet Isaiah ben Amoz, but there is extensive evidence that much of it was composed during the Babylonian captivity and later. The consensus through most of the 20th century, that the book comprises three separate collections of oracles: Proto-Isaiah (chapters 1-39), containing the words of Isaiah; Deutero-Isaiah (chapters 40-55), the work of an anonymous 6th-century BCE author writing during the Exile; and Trito-Isaiah (chapters 56-66), composed after the return from Exile. While virtually no scholars today attribute the entire book, or even most of it, to one person, the book's essential unity has become a focus in current research.