The Trinity

The Trinity is grounded in three movements of biblical data that must all be held together:

(1) The absolute monotheism of Scripture: "Hear, O Israel: the LORD our God, the LORD is one" (Deuteronomy 6:4, the Shema). "I am the LORD, and there is no other, besides me there is no God" (Isaiah 45:5). The New Testament inherits and affirms Jewish monotheism: "God is one" (Romans 3:30, Galatians 3:20, 1 Timothy 2:5, James 2:19). The Trinity is never the abandonment of monotheism.

(2) The full deity of Father, Son, and Spirit asserted separately:

-- Father: "One God, the Father, from whom are all things" (1 Corinthians 8:6).

-- Son: "In the beginning was the Word, and the Word was with God, and the Word was God" (John 1:1). "My Lord and my God" (John 20:28, Thomas's confession). "In him the whole fullness of deity dwells bodily" (Colossians 2:9). "He is the radiance of the glory of God and the exact imprint of his nature" (Hebrews 1:3).

-- Spirit: "You have not lied to men but to God" (Acts 5:3-4, lying to the Holy Spirit is lying to God). "The Spirit of God" who was present at creation (Genesis 1:2) and who raised Christ from the dead (Romans 8:11).

(3) The distinct personal identities of Father, Son, and Spirit: the Father sends the Son (John 3:16-17); the Son prays to the Father (John 17); the Father and Son send the Spirit (John 14:26, 15:26); the Spirit intercedes before the Father (Romans 8:26-27). These are not roles played by one person but real personal relationships. At the baptism of Jesus: the Father speaks, the Son is baptized, the Spirit descends as a dove (Matthew 3:16-17), three simultaneous presences.

The Trinitarian formula of Matthew 28:19, "baptizing them in the name (onoma, singular, not plural) of the Father and of the Son and of the Holy Spirit", uses the singular "name" for three persons, encapsulating the paradox: one name, three persons.

The Nicene Creed (325 AD; expanded at Constantinople 381 AD) did not invent the Trinity but gave it precise grammatical expression to exclude the distortions that kept appearing:

Key heresies the councils were ruling out:

-- Modalism (Sabellianism): one God who successively plays three roles or modes (Father in OT, Son in incarnation, Spirit in church age). Ruled out because the NT presents Father, Son, and Spirit in simultaneous, genuinely relational presence (John 17; baptism of Jesus).

-- Subordinationism (Arianism): the Son is a created being, highest of creatures, but not co-eternal with the Father. "There was a time when he was not" (Arius, circa 318 AD). Ruled out by Nicaea: homoousios (ὁμοούσιος, of the same essence/substance as the Father).

-- Tritheism: three separate gods. Ruled out by the consistent biblical monotheism.

The developed Trinitarian grammar (Basil of Caesarea, Gregory of Nyssa, Gregory of Nazianzus, the Cappadocian Fathers, 4th century):

-- One ousia (οὐσία, essence, substance, being): one what; the divine nature shared equally by all three persons

-- Three hypostaseis (ὑπόστασις, person, particular instance, subsistence): three who's; distinct personal realities, not merely different names for the same entity

-- The persons are distinguished by their eternal relations: the Father is unbegotten; the Son is eternally begotten of the Father (not created, "begotten not made," Nicene Creed); the Spirit proceeds from the Father (and the Son, in Western theology, the filioque addition, which divided East and West in 1054).

Perichoresis (περιχώρησις, lit. rotation around, mutual indwelling; Latinized as circumincessio) is the patristic term (developed by John of Damascus, 8th century, systematizing the Cappadocians) for the mutual indwelling of the three persons in one another.

The biblical ground is John 14:9-11: "Do you not believe that I am in the Father and the Father is in me?... the Father who dwells in me does his works. Believe me that I am in the Father and the Father is in me." John 10:38, "the Father is in me and I am in the Father." John 17:21, "as you, Father, are in me, and I in you, that they also may be in us."

Perichoresis conveys: the three persons are not three separate divine "beings" who happen to share the same nature. They mutually indwell and coinhere, the Father is always already in the Son and Spirit; the Son in the Father and Spirit; the Spirit in the Father and Son. The three are not separate containers of divinity but three persons who fully exist in one another without confusion or mixture.

The doxological implication: when the New Testament calls believers to participate in the divine life ("that they also may be in us", John 17:21; "partakers of the divine nature", 2 Peter 1:4), this is an invitation into the relational life of the Trinity itself, not mere moral improvement. Salvation draws us into real communion with the Triune God, union with Christ, adoption as sons, and final glorification. This is genuine participation in His life by grace, yet we never become God by nature; the Creator-creature distinction always stands.

The Sanctum treats the Trinity not as an ecclesiastical formula to be memorized but as the disclosure of who YHWH actually is. The God who created the world is not a solitary monad but a community of persons in eternal self-giving love. The cross is not a transaction within a single divine will but the sending of the Son by the Father, and the Spirit's application of that gift to those who believe. The prayer life of the church is addressed to the Father, through the Son, in the Spirit (Ephesians 2:18, "through him we both have access in one Spirit to the Father"). Every Christian prayer is Trinitarian.