Why is there one God but also three (Trinity)?
Christians believe in one God who exists as Father, Son, and Holy Spirit. This truth, called the Trinity, has always been at the heart of Christian faith. From the earliest centuries, believers confessed it in their worship, prayers, and creeds.
This is also what makes Christianity unique. Other religions may speak of many gods or of a single, solitary god. But Christianity proclaims something different: one God in three persons—a mystery revealed in the Bible and held firmly in the church throughout history.
Trinity in the Creeds
The word “Trinity” doesn’t appear in the Bible, but it’s a helpful way to describe what Scripture teaches about God’s tri-unity.
The Nicene Creed (AD 325, revised 381) gives us one of the clearest summaries of this belief:
“We believe in one God, the Father Almighty…And in one Lord Jesus Christ, the only-begotten Son of God… true God from true God… of one essence with the Father…And in the Holy Spirit, the Lord and Giver of life, who proceeds from the Father [and the Son], who with the Father and the Son together is worshiped and glorified.”
In other words, there is one divine essence and three distinct persons. The Athanasian Creed puts it even more strongly:
“We worship one God in Trinity, and Trinity in Unity, neither confounding the persons nor dividing the substance… This is the catholic faith; whoever does not believe it faithfully and firmly cannot be saved.”
Throughout Christian history, denying the Trinity has been regarded as departing from the true faith.
Trinity in the Bible
The Trinity is not built on human philosophy but on God’s Word. The Bible teaches two truths side by side: there is only one God, and the Father, Son, and Spirit are each fully God.
God is One
“Before me no god was formed, nor shall there be any after me.” (Isaiah 43:10)
“Hear, O Israel: The LORD our God, the LORD is one.” (Deuteronomy 6:4)
Yet even from the opening pages of Scripture, God hints at His triune nature: “Let us make man in our image” (Genesis 1:26).
God is Three
The Father is God—Jesus prays to Him as such (John 17:1–3).
The Son is God—“In the beginning was the Word, and the Word was with God, and the Word was God… and the Word became flesh.” (John 1:1, 14). Thomas later confesses to Jesus: “My Lord and my God!” (John 20:28).
The Holy Spirit is God—lying to the Spirit is lying to God Himself (Acts 5:3–4).
These passages, along with texts like Matthew 28:19 and 2 Corinthians 13:14, show us both the oneness and the threeness of God.
The Trinity is a mystery
The Trinity is a mystery—something bigger than our minds can fully grasp. And when people have tried to make it easier to explain, they often slip into error.
- Modalism: God is one person who just shows up in three different “modes.” But Scripture shows the Father, Son, and Spirit active together (like at Jesus’ baptism, Matthew 3:16-17).
- Tritheism: There are three separate gods. But the Bible insists there is only one God.
- Arianism: The Son was created and not eternal. This was condemned at the Council of Nicaea.
- Partialism: Each person makes up one-third of God. But each person is fully God.
Even popular analogies—like water being liquid, ice, and vapor—fall short. God is not like created things. Instead, Christians simply confess what Scripture reveals, even if we can’t fully explain it. After all, a God who could be completely grasped by human reason would not be much of a God.
Why the Trinity matters
The Trinity matters for everyday faith. First, it shows us that God is love (1 John 4:8). Love requires relationship, and from eternity the Father, Son, and Holy Spirit have shared perfect fellowship. Out of that love, God draws us in—Jesus prayed that His followers would share in the love the Father has for Him (John 17:24-26). Love is not just what God does; it is who He is.
The Trinity also shapes our salvation. The Father lovingly sent the Son into the world (John 3:16). The Son accomplished redemption through His death and resurrection (Romans 5:8; 1 Corinthians 15:3-4). And the Holy Spirit applies that salvation to us, dwelling within us and giving us new life (Romans 8:9-11; Titus 3:5). From beginning to end, our redemption is the work of the triune God.
