Tim Chester is surely right, and summarises his entire book, when he says that, "Many of us find the doctrine of the Trinity - that God is three persons sharing one nature - difficult to get our heads round and frankly a bit embarrassing. What is more, we seem to get by without it. But in reality the Trinity is at the heart of all we believe. The Trinity gives shape to Christian truth. Many people claim to believe in God, but have no time for Him. That is because their "god" is remote and uninvolved. The triune God sent His Son into human history so that we could know Him as our Father, and He sends His Spirit to accompany us in the struggles of life. To find out more about this God is a wonderful adventure."
To outline the book even more briefly, we could say that the triune God revealed in the Bible is good news, and so the Trinity must be good news; while the doctrine of the Trinity is a mystery, it is not an absurdity.
Tim goes on to consider the twin themes of the unity and the plurality of God as portrayed in the Bible. Beginning with God's unity, he reminds us that at the heart of Israelite faith was the so-called Shema: "The Lord our God, the Lord is one". It affirms the uniqueness and oneness of God as well as His identity as the God of Israel. The New Testament weaves Jesus into the Shema, identifying Him as the Lord without compromising the oneness of God. God is one, undivided and singular. Father, Son and Spirit speak with one voice because they are one. God's words are always consistent, and Yahweh has a unity of will and a constancy of character. With regard to God's plurality, there are signs in the Old Testament that the one God is also in some sense plural. The coming of Jesus fully illuminates the trinitarian nature of God, and the doctrine of the Trinity developed as a way of summarising what we discover in the story of salvation. Jesus is the definitive hermeneutic of both the Old and the New Testaments, and renders compelling the evidence for God's plurality.
God's unity and plurality are seen most clearly at the cross. We need the Trinity to make sense of the cross, and we cannot understand the cross without both the unity and the plurality of God. The cross shows us that there are distinctions within God, as God can be forsaken by God. Equally, if God is not one, then the cross becomes a cruel and vindictive act with an angry Father punishing an unwilling Son or a loving Son placating an unwilling Father. Only if God is one can the cross be for us reconciliation and inclusion within the divine community. The cross reveals God, and God is a Trinity of Father, Son and Spirit.
Tim then goes on to sketch out the development of the doctrine of the Trinity throughout church history:
- 2nd–4th Centuries AD: The Trinity expresses God's actions versus the Trinity expresses God's being. The first Christian theologians thought about the Trinity as an expression of God's actions towards His creation, so God became the Trinity in history. But soon theologians began to recognise that God's actions must reflect His eternal being. Father, Son and Spirit were not different modes of God's activity, but three eternal persons sharing one divine substance.
- 5th–16th Centuries AD: Starting with the threeness of God versus starting with the oneness of God. The division between East and West created two different trajectories in trinitarian theology. The East started with the threeness of God, seeing the Father as the fountainhead of the Trinity, with the Son and Spirit deriving their divinity from Him. The Western tradition started with the One God, defining the three persons by their eternal relations. From a Western perspective, the danger of Eastern trinitarianism has been a tendency towards subordination (making the Son and Spirit inferior to the Father) or even tritheism. On the other hand, Western theology has tended toward modalism, in which the unity of God obscures the threeness of God.
- 17th–20th Centuries AD: The Trinity at the margins of theology versus the Trinity at the centre of theology. The Protestant Reformers had a vision of God which was fundamentally different from anything which had gone before, or which has appeared since. The great issues of Reformation theology - justification by faith, election, assurance of salvation - can be properly understood only against the background of a Trinitarian theology which gave these matters their peculiar importance. The Enlightenment, with its emphasis on what could be known through human reason, had little time for the Trinity. It either thought of God as a remote deity or regarded the Trinity as of marginal significance, and so the Trinity has been pushed to the edge of the theology of our liberal mainline denominations.
Finally, Tim ends his book by reflecting on the implications of the Trinity on some key themes:
- The Trinity and revelation: God can be known personally because He is a Trinity of persons in relationship. He has revealed Himself in His Son and enables us to recognise this revelation by His Spirit.
- The Trinity and salvation: At its heart, salvation is a transaction within the Trinity. The Son offers Himself to the Father as our substitute. God both judges and is judged. And the Spirit applies this transaction to our lives.
- The Trinity and humanity: We were made in the image of the triune God. We find our identity through relationships. Just as there is both unity and plurality in God, so communal identity should not suppress individual identity, and individual identity should not neglect communal identity. The church should be a community of unity without uniformity and diversity without division.
- The Trinity and mission: The Trinity is a missionary community. The Father sent His Son and His Spirit into the world to redeem His people, so the Trinity is good news. God does not assert His identity against ours, but invites us to find true identity by sharing His community. The ultimate apologetic for the Trinity is the Christian community.
This is a fine and very readable introduction to and overview of the doctrine of the Trinity. Tim Chester puts this crucial doctrine firmly where it belongs, at the core of our belief and practice.