Although defined as ‘the central dogma of Christian theology’ (1) the term Trinity is nowhere explicitly stated in Scripture. Rather, it is a sublime concept, progressively revealed by God in His Word, which is nevertheless capable of deduction and acceptance by the finite minds of humankind. A classic description is ‘one God subsisting in three persons and one substance’. The words ‘persons’ and ‘substance’ are highly specific in this context – we will return to them later. Whatever the Trinity means, it must therefore be fundamental to understanding who God is and what God does. The figures one and three are crucial to such understanding. Christianity will emphatically concur with the Jew and the Moslem that ‘the Lord our God is one Lord’ (2), but will add that He subsists in three Persons. This fundamental qualification accounts for the continuing opposition of Judaism to Christianity, ever since the Son of God declared, “I and the Father are one” (3). It also places Christianity at complete odds with Moslem monotheism (4).

This may already seem remote and complex, but the implications are also fundamental in a much more human way. For John to declare that ‘God is love’ (5) has little real meaning unless God had somebody to love before He created mankind in His own image – love involves at least two persons. Jesus insisted that the Father loves the Son with absolute candour and unity of purpose (6). This sublime love, subsisting and streaming eternally between the Persons of the Trinity, is presented to us as the fount of all human love (7). Explaining the Trinity – principles Basic as this doctrine is, it has never ceased to be controversial. For some people, the intellectual difficulty of encompassing a God who is both one and three, is enough for the Trinity to be relegated to the theological back burner or even rejected. There are therefore some basic principles by which the disciple will wish to be guided:

1. We are used to complexity, both in our everyday lives and in the creation around us. Can we expect the Creator – immortal, living in light unapproachable, majestic in holiness – to be any more accessible to our finite minds?
2. The Trinity, like all of Scripture, is the product of divine revelation, and God knows how much revelation we can endure of His ineffable glory. There are secret things which belong only to Him, and surely the fullness of the relationships within the Trinity is one of these. Nevertheless, the things revealed belong to us (8) – assuring us that the Spirit will use meditation on these high and holy revelations to enrich our spiritual lives.
3. There are limitations imposed by our human condition in considering the nature and character of God. One is language, by which God has chosen to reveal Himself, but which is nevertheless inadequate to the task of communicating His reality. We therefore need to be very careful about the words that we use, recognising their limitations.

Another limitation is our environment, particularly our domination by time. We are driven to use analogies in seeking to explain and defend the Trinity. There is nothing wrong with this approach, provided we are sensitive to the limitations implicit in comparing a thing or a state with the eternal and limitless. For example, in describing the unity and diversity of the Trinity we may choose the analogy of a man who is at once a husband, father and son, uniting three different functions in one person. This is helpful as far as it goes, but it fails to do full justice to the relationships within the Trinity which demand equality and universality as well as diversity (9). So, confronted by these ineffable facts about God, the humble disciple can only wonder and adore, being content to accept the Trinity as a doctrine which accommodates all the relevant Scriptural revelation. The process thereafter of pursuing analogies which go some way towards explaining it in human terms is legitimate, but to proceed the other way – fitting the doctrine into an allegorical system – is likely to skew and oversimplify any attempt to understand the revealed nature of God.

A little history … One important example of an unbalanced approach to the Trinity is afforded by the Arian controversy of the fourth century. Arius (c.250-336) taught that Christ, though creator and redeemer, was not of one substance with the Father, being born in time. The root of his error lay precisely in over-emphasising selective Scriptures at the expense of the whole revelation, considering the eternal truths of Christ’s divine nature through the perspective of space and time, and in failing to acknowledge the limitations of language in expressing this divine nature. John repeatedly describes the Son as being the only begotten of the Father (10). Arius interpreted this, in conjunction with certain Scriptures implying order in the Trinity (11) in a space/time context so as to indicate that Christ was willed into existence by God.

A similar stumbling block was provided by the Greek word ‘hupostasis’ in the context of Hebrews 1:3 – the image of his substance (RV) in relation to the nature of Christ. Here is a material word – meaning basis or foundation – used by the Spirit-guided writer in a highly technical, theological sense (12). Arians argued that the Son was not of the same substance, but of a like substance, with the Father, again suggesting that the Son is inferior. So serious were the implications of this teaching, that a Council was held at Nicea in 325 AD, resulting in the famous credal formulation describing the Son as ‘begotten not made, being of one substance with the Father’. A later Council described the Spirit as ‘the Lord. … who proceeds from the Father and the Son and with the Father and the Son together is worshipped and glorified.’ These classic formulations have stood the test of time, because they take account of the full Scriptural revelation about the Trinity – particularly those which emphasise the eternal existence of the Son in equality with the Father (13) and the divine nature of the Lord the Spirit (14).

These remote debates continue to resonate today. Arian interpretations of monotheism are still propounded by various unitarian groups and by sects such as the Jehovah’s Witnesses. And the Nicean debates still leave some loose ends, such as the use of the word ‘Person’ to describe the Trinity. This word requires cautious use in this context – in the normal sense ‘persons’ signifies individuals with different knowledge, feelings and will. But in the theological sense, these qualities are all identical (15). What is God – one in three There are many instances, some already referred to (13,14) which make clear the divine nature of the Son and the Spirit, both sharing the attributes of the Father. One particularly noteworthy example is the Great Commission (15) where the risen Lord enjoins the disciples to baptise in one name – God – but in all three Persons. It will have been noted that nearly all the references above are to the New Testament, but it is clear that the Trinity is also at work before the incarnation.

Even in the uncompromising monotheism of Deuteronomy 6:4, the word ‘echad’ describes ‘one’ God not in isolation but one in unity, for example as in a bunch of grapes or one people. Turning to the New Testament, it is unsurprising that the work of the Trinity is particularly evident during the ‘days of his flesh’ – in Christ’s incarnation (16), baptism (17) and resurrection (18) and in the act of atonement (19). However, focusing on the essential unity of will and work implicit in the Trinity is only part of the story and can, again, skew our understanding of this sublime truth. Before even Arius, the Sabellians taught that Father, Son and Spirit were only temporary manifestations of the one God, assumed for the purpose of redemption. This error has the apparent virtue of ‘simplicity’ and is therefore still alive today, but it fails to do justice to the Scriptural revelation of diversity in the Trinity, to which we now turn.

One of the most beautiful and comforting of Scriptures is surely the apostolic blessing (20) This indicates that we are right to discern a diversity of function in the Trinity – in this case, all directed towards us! Other Scriptures point us towards distinctive focuses of the work of each Person (21) and in specific areas – such as creation (22) – particular functions are very evident. Ascribing set roles to each Person (modalism), by which God as Father provides and creates, while in His role as Son He redeems and lives in believers in the mode of the Spirit, is far too restrictive. For example, there are aspects by which all three Persons abide within the heart of the believer (23). So where do we conclude? While recognising that the Trinity is not to be pigeonholed by our puny minds, we may safely summarise that God reveals Himself to us as God above (24) God beside (25) and God within (26) and that these are particular (but not exclusive) focuses of the respective Persons of the Trinity.

References: (1) The Oxford Dictionary of the Christian Church (2) Deut. 6:4 RV (3) Jn.10:30 (4) “Do not speak of a Trinity … God is only one God, He is far above having a Son.” Qu’ran 4:171 (5) 1 Jn.4:8 (6) Jn.3:35; 5:20, cf. Col.1:13 (7) 1 Jn.4:7-21 (8) Deut.29:29 (9) Jn.1:1; 1 Cor.2:10-11 (10) Jn.1:14,18 RV (11) Such as Jn.14:28 and 1 Cor.8:5-6. That there is order in the Trinity is clear (“The Father is greater than I”) but, taken with other Scriptures, it is also clear that this does not imply inferiority. (12) The difficulties of rendering this word in a way which is meaningful is demonstrated by the variety of English translations. (13) e.g. Jn.10:30 (“I and the Father are one”): Jn.1:1; Col.2:9 (All the fullness of the Deity) (14) e.g. Ps.139:7; 1 Cor.2:10-12; Jn.14:16 RV (“another Comforter”, literally “another of the same kind”); Acts 5:1-4 (15) Matt.28:18-20 (16) Lk.1:35 (17) Lk.3:21-22 (18) Jn.10:17-18; Rom.6:4; 8:11 (19) Heb.9:14 (20) May the grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all (2 Cor.13:14) (21) e.g. Jude 20-21 (22) Gen.1:1-2; Jn.1:3 (23) 1 Jn.4:13-15; Jn.14:23; 2 Cor.1:21-22 (24) Gen.1:1-3 (25) Matt.1:23; 28:20 (26) Jn.14:15-18; Acts 1:8

Bible quotations from NIV unless otherwise stated.