Modalism
In one sentence
An anti-Trinitarian model in which Father, Son, and Spirit are understood as manifestations of one divine Person.
In simple terms
God is understood as one Person who reveals himself as Father, Son, or Holy Spirit rather than as three eternally distinct Persons.
Biblical truth
Scripture affirms one God while also distinguishing Father, Son, and Spirit from one another, including scenes in which they act simultaneously.
Key Scriptures
Matt. 3:16–17 · Matt. 28:19 · John 1:1–2 · John 14:16–17 · 2 Cor. 13:13
Example
In a modalist framework, the Son praying to the Father is explained without positing two distinct divine Persons.
Who holds it
Historically, modalistic Monarchians and Sabellians; today a closely related view is found in Oneness Pentecostalism.
Opposing view
Trinitarianism
Not to be confused with
Not to be confused with Trinitarianism, which affirms one God and a real, eternal distinction among Father, Son, and Spirit.
History
Modalistic forms of Monarchianism spread in the second and third centuries; Sabellius became especially associated with one such form.
Main point of debate
The central question is whether the biblical distinctions among Father, Son, and Spirit require three eternal Persons rather than three manifestations of one Person.