Where in Isaiah Is the Third Person of the Trinity Mentioned?

Judaism doesn't recognize a Trinity, so the framing of this question — locating the "third person" of a triune God — doesn't apply to Jewish theology. That said, the underlying Hebrew text of Isaiah is Jewish scripture, and the passage most often cited by Christians is worth examining from a Jewish perspective.

Isaiah 63:11 reads, in the KJV: "where is he that put his holy Spirit within him?" Isaiah 63:11 The Hebrew here is ruach qodesh (רוּחַ קָדְשׁוֹ), which Jewish interpreters — from the ancient rabbis through medieval commentators like Rashi (1040–1105) — consistently understand as God's divine power or presence, not a distinct hypostatic person. The verse is a historical lament recalling the Exodus, asking where the God who empowered Moses has gone. It's a rhetorical expression of longing, not a theological statement about divine persons.

The Talmud engages extensively with Isaiah but never treats ruach qodesh as a separate being. Talmudic literature uses the term to describe prophetic inspiration — a quality or force, not a person Berakhot 4b:25. The concept of God's absolute unity (yichud) is foundational in Judaism, making any tripartite reading of these texts a fundamental departure from the tradition's own interpretive framework.

This question is most directly a Christian one, and it's worth being honest: the word "Trinity" never appears in Isaiah. What Christians identify are anticipatory references — passages that, read through a New Testament lens, seem to point toward the Holy Spirit as the third person of the Godhead.

The most frequently cited passage is Isaiah 63:11, which asks "where is he that put his holy Spirit within him?" Isaiah 63:11 Patristic writers and later Reformed theologians like John Calvin (writing in his 1559 Institutes) saw this as evidence that the Spirit was active in the Old Testament economy, not merely a New Testament phenomenon. The verse's context — a communal lament over God's apparent absence — gave early Christians a framework for understanding the Spirit as a distinct, personal agent who could be "grieved" (cf. Isaiah 63:10, just before this verse).

It's important to acknowledge real disagreement here. Critical scholars like Joseph Blenkinsopp, in his 2003 Anchor Bible commentary on Isaiah 56–66, argue that reading Trinitarian theology into these verses is anachronistic. The text's original intent, he contends, was to describe God's powerful presence with Israel during the Exodus — not to outline a doctrine of divine persons that wouldn't be formally articulated until the Council of Nicaea in 325 CE.

Some Christians also point to Isaiah 63:7–14 more broadly as a passage where Father ("the LORD"), the "Angel of His Presence" (sometimes read as the Son), and the "holy Spirit" appear in proximity — a so-called "Trinitarian pattern." This reading is common in conservative evangelical scholarship but is contested even within Christianity itself.

Isaiah 54:5 is occasionally cited in adjacent discussions, where God is described as "Maker," "LORD of hosts," and "Redeemer" Isaiah 54:5 — though this is more often used to argue for divine complexity than specifically for the Spirit.

Not applicable. The doctrine of the Trinity — including the concept of a "third person" — is a specifically Christian theological construct. Islam explicitly rejects the Trinity as incompatible with tawhid (the absolute oneness of God), and Islamic theology does not engage with Isaiah as a source of doctrinal authority. There is therefore no Islamic framework within which to locate a "third person of the Trinity" in any scripture.

Not applicable. Concerns Christian doctrine of the Trinity; no direct counterpart in Jewish doctrine is intended by the question. Isaiah 63:11

Christians who ask where Isaiah mentions the third person of the Trinity typically point to Isaiah 63:11, which refers to “his holy Spirit.” Isaiah 63:11 The wording indicates that God placed His holy Spirit among or within His people in the Exodus memory, and this is read as a key Old Testament witness to the Spirit’s work. Isaiah 63:11 Readers also note that while the verse plainly says “holy Spirit,” it does not present an explicit Trinitarian formula within the verse itself; the Trinitarian reading is theological inference from the scriptural language. Isaiah 63:11

Not applicable. The question targets a Christian Trinitarian reading of Isaiah; Islam does not frame Isaiah in Trinitarian terms. Isaiah 63:11