treenighet

Treenigheten is the central doctrine in mainstream Christianity that the one God exists as three coequal, coeternal persons: the Father, the Son, and the Holy Spirit. The term comes from Latin trinitas and has been transmitted into Scandinavian languages, where treenighet expresses the idea of a unity in plurality.

Core elements include the belief that God is one in essence (ousia) but three distinct persons (hypostases). Each person is fully God, yet they are not three gods but one. The relationships among the persons are real, not merely roles or modes of God, and the doctrine seeks to preserve both unity and distinction. The concept of perichoresis describes a mutual indwelling among the three persons, so they coexist in a dynamic unity. There is also discussion of the immanent Trinity (God’s internal life) and the economic Trinity (God’s actions in creation and salvation).

Historically, the doctrine was clarified through early ecumenical councils. The Council of Nicaea (325) affirmed that the Son is of the same essence as the Father. The Council of Constantinople (381) affirmed the divinity of the Holy Spirit. The Cappadocian Fathers helped articulate the distinctions between ontological essence and personal relations. The West’s adoption of the filioque clause—that the Spirit proceeds from the Father and the Son—generated lasting East–West tensions. Over time, these formulations became standard in Catholic and Protestant and most Orthodox theology, though nuances remain.

Today, treenigheten remains a defining feature of most mainstream Christian denominations. Some groups, known as nontrinitarian, reject the doctrine or hold alternatives about the nature of God and Jesus. The doctrine continues to shape theology, creeds, and liturgical tradition.