The doctrine of the Trinity is, as someone once said, ‘the glory of the Christian religion’. It is the doctrine that defines orthodoxy, the doctrine that guarantees our knowledge of God, and the doctrine that secures our salvation. In the first four centuries, Christians worked very hard to articulate and defend this key belief, and we are all beneficiaries of their work.
Key ancient figures
The major debates over the Trinity took place between the 3rd and 5th centuries AD. The two most significant councils in this regard were the Council of Nicea (325) and the Council of Chalcedon (451). The Council of Nicea defended the deity of Jesus Christ by asserting that he was ‘of the same substance’ (Gk, homoousion) as God the Father. The Council of Chalcedon set limits for Christian reflection on the person of Jesus, by showing that Jesus was truly God and truly man—one person with two natures.
Two key figures in these debates were Athanasius (296-373) and Augustine (354-430). Athanasius was an eastern theologian, who almost single-handedly defended the Christian faith from the threat of Arianism. The Arians (named after Arius, their founder) were the ancient counterpart to modern Jehovah’s Witnesses. The Arians taught that Jesus was inferior to God the Father, that he was created (rather than co-eternal with the Father), and was thus not fully divine. One of their famous slogans was: “There was a time when he was not”. Arianism is sometimes also known as ‘subordinationism’, since it holds that the Son is subordinate in essence and being to the Father.
Augustine’s battle was slightly different. He helped Christians to understand the grace of God, and thus defended the church from Pelagianism (salvation by works). However, his writings on the Trinity were also voluminous and very influential.
Augustine and Athanasius, along with other figures from this era, are sometimes referred to as the fathers.
Key modern figures
Robert Doyle’s article also interacts with two modern theologians, Karl Barth and Karl Rahner. Karl Barth was probably the leading Protestant theologian of the 20th century, and did much to re-articulate orthodox Christianity at a time when liberalism was undermining key doctrines. His treatment of the Trinity has been very influential in theological circles. Karl Rahner was a very significant Roman Catholic theologian, and was probably the most significant intellectual force behind Vatican II—the council that defined Roman Catholicism for the 20th century.
Some key terms
The immanent Trinity: This refers to the Trinity as it really is in eternity. Discussion about the immanent Trinity concerns who God is in himself, and how the three persons of the Trinity relate to each other eternally.
The economic Trinity: Theologians often talk about the ‘economy’ of salvation, which is their way of talking about God’s work in the world: how he went about revealing himself in history, and acting to bring about the salvation of mankind. The economic Trinity is that aspect of the Trinity that is revealed in human history as God acts—for example, in the Word becoming flesh and living amongst us. It’s important to differentiate between these two aspects of the Trinity because there are some things that are true of God in eternity (e.g. that he is all-knowing), but are not true of God the Son when he became man (e.g. he didn’t know all things).
Ontology: This is a philosophical term, which refers to the study of ‘being’. What does it mean to exist, to be? What is the being of God like? What is his essence? These are the questions of ‘ontology’.
Order: In this context, ‘order’ refers to how things relate to other things. In the creation, are plants ordered to (ordained for) animals for food, or do they just happen to taste good? In human relations, are men and women ordered to each other in any way? And—the big question—is there order in God? Is there any sense in which Father, Son and Holy Spirit relate to each other in any ordered way? For example, in the Bible, we see that the Father gives commands to the Son. Is this just a part of the economy of salvation, or does it tell us something about the way the Trinity is ordered in eternity? These are big questions, and they are at the heart of Robert Doyle’s essay.
Perichoresis: A term meaning ‘to mutually indwell’, used to describe the inner relation of the persons of the Trinity. As Karl Barth expresses it: “The divine modes of being mutually condition and permeate one another so completely that one is always in the other two”.