Trinity

The Trinity is the central Christian doctrine that the one God eternally exists as three co-equal, co-eternal, distinct persons — Father, Son, and Holy Spirit — one in being (Greek ousia) yet three in person (hypostasis). The word itself is not in Scripture, but it names what Scripture everywhere assumes: rigorous monotheism — "the LORD our God, the LORD is one" (Deuteronomy 6:4; Isaiah 44:6) — together with the full deity of three distinct persons. It is not tritheism (three gods) nor modalism (one person in three masks), but one God subsisting eternally as Father, Son, and Spirit.

The Old Testament lays the foundation: uncompromising monotheism, yet with hints of plurality within God — "Let us make man in our image" (Genesis 1:26) — and the Spirit of God and the Word of God acting as divine agents. The full disclosure comes in the New Testament. The Father is God; the Son is God — "the Word was God" (John 1:1), confessed by Thomas as "My Lord and my God" (John 20:28) and called "our great God and Savior" (Titus 2:13); and the Spirit is God, for to lie to the Holy Spirit is to lie to God (Acts 5:3–4). Yet there is "one God, the Father… and one Lord, Jesus Christ" (1 Corinthians 8:6).

The three persons appear together in the great triadic texts: at Jesus’ baptism the Son is baptized, the Spirit descends, and the Father speaks (Matthew 3:16–17); the Great Commission baptizes "into the name" — singular — "of the Father and of the Son and of the Holy Spirit" (Matthew 28:19); and the apostolic blessing joins all three (2 Corinthians 13:14; cf. 1 Peter 1:2). The persons are distinct in relation yet undivided in essence: the Son is eternally from the Father (John 1:14), the Spirit proceeds from the Father (John 15:26), and "I and the Father are one" (John 10:30; John 14:9).

The doctrine is no mere abstraction. It safeguards both monotheism and the full deity of Christ and the Spirit, and it reveals that God is eternally relational — "God is love" (1 John 4:8) within himself before creation. Salvation itself is Trinitarian: the Father sends the Son to redeem and the Spirit to apply that redemption, making believers sons who cry "Abba, Father" (Galatians 4:4–6; Ephesians 1:3–14). Defined against Arian subordinationism and Sabellian modalism at the Councils of Nicaea (AD 325) and Constantinople (AD 381), it is confessed in the Nicene and Athanasian Creeds as the bedrock of Christian worship.

The three persons

God the Father — the unbegotten source and fountain of the Godhead, who sends the Son and pours out the Spirit.

God the Son — eternally begotten of the Father, who became incarnate as Jesus Christ for our salvation.

God the Holy Spirit — who proceeds from the Father, gives life, and applies redemption to God’s people.