Our Triune God is not like anything on earth. It is therefore no surprise that the church struggled to find appropriate words to speak about the Trinity. We want to avoid partialism, the suggestion that God consists of three separate parts. But we should also shun modalism, where God is described as one individual person playing different roles, as it were.
Around 210 AD, church father Tertullian introduced Latin terminology that we still use. He spoke of trinitas, “threeness”; and of persona, “individual person”. He said that the Son is “from the substantia of the Father.” Today we would have some issues with Tertullian’s understanding of the Trinity, but we still use the language he introduced.
A century later, the well-known heretic Arius denied that the Son of God is himself divine. This forced the church to make official pronouncements about the nature of the Trinity. The discussion took place in the Greek-speaking part of the church. The council of Nicaea (325 AD) drafted (an early version of) the Nicene Creed, which described the Son as homoousios, “of the same essence” or “consubstantial” with the Father.
But the language of the council of Nicaea was not precise enough to defeat the false teachers. It had rejected the idea “that the Son of God is of another hypostasis [subsistence] or ousia [being, substance]” than the Father. But these words had a broad range of meaning, so that the controversy was not really solved. The heated debates continued throughout the fourth century.
In 381, the Council of Constantinople dealt with the question again. A more precise way of speaking was developed:
- God is one ousia (“being”), physis (“nature”); Latin: substantia or essentia.
- Father, Son, and Spirit are three hypostases, or prosôpa (“faces”); Latin: subsistentiae or personae.
This became the official language of the church. A detailed statement of the traditional doctrine of the Trinity can be found in the Athanasian Creed (Book of Praise, p. 495).
This history shows a more general tension in Christian theology. In the study of theology, we need precise words, and these are often borrowed from philosophical terminology; but we wish to avoid philosophical speculation and must always return to the way God speaks of himself. A great example of this balance is the plain description of the Trinity in Heidelberg Catechism, q&a 25.
In her worship, the church is wise to avoid the technical terms, and focus on the language of Scripture: Praise to the one true God, and praise to Father, Son, and Holy Spirit.
Robert Letham, The Holy Trinity. In Scripture, History, Theology, and Worship. P&R Publishing, 2004. p. 89-183.
Jaroslav Pelikan, The Christian Tradition. A History of the Development of Doctrine. Volume 1: The Emergence of the Catholic Tradition (100-600). Chicago, 1971. Chapter 4: “The Mystery of the Trinity”, p. 172-225.