Trinitarianism
In one sentence
The doctrine that the one God eternally exists as three Persons: Father, Son, and Holy Spirit.
In simple terms
God is one, yet Father, Son, and Holy Spirit are neither one Person nor three gods.
Biblical truth
Scripture affirms one God, identifies Father, Son, and Holy Spirit as divine, and also distinguishes them personally.
Key Scriptures
Deut. 6:4 · Matt. 28:19 · John 1:1–3 · Acts 5:3–4 · 2 Cor. 13:13
Example
In Matthew 28:19 one “name” is associated with Father, Son, and Holy Spirit.
Who holds it
Nicene Christianity: Orthodox, Catholic, and the great majority of Protestant traditions.
Opposing view
Unitarianism · Modalism · Arianism · Tritheism · Oneness Pentecostalism · Dynamic Monarchianism · Patripassianism
Not to be confused with
Not to be confused with tritheism (three gods) or modalism (three modes of one Person).
History
Trinitarian terminology was refined in early Christian controversies and received classical expression in the Nicene-Constantinopolitan Creed.
Main point of debate
Debates concern the precise relations of the Persons, eternal generation of the Son, and procession of the Spirit.