Oneness Pentecostalism is a nontrinitarian religious movement within the Protestant Christian family of churches known as Pentecostalism. It derives its name from its teaching on the Godhead, a form of Modalistic Monarchianism commonly referred to as the Oneness doctrine. The doctrine states that there is one God―a singular divine spirit with no distinction of persons―who manifests himself in many ways, including as Father, Son, and Holy Spirit. This stands in sharp contrast to the doctrine of three distinct, eternal persons posited by Trinitarian theology.

Nontrinitarianism is a form of Christianity that rejects the mainstream Christian theology of the Trinity—the belief that God is three distinct hypostases or persons who are coeternal, coequal, and indivisibly united in one being, or essence. Certain religious groups that emerged during the Protestant Reformation have historically been known as antitrinitarian.