Letham, Robert. The Holy Trinity: In Scripture, History, Theology and Worship. Phillipsburg, NJ: P & R Publishing, 2005.
This is an outstanding book. Letham begins with an overview of the Biblical doctrine of the trinity. He then describes the historical development of the doctrine of the trinity from the early church to the present, covering both the orthodox and heterodox. The book closes with an excellent overview of how the trinity ought to inform our life and worship.
While the entire book is very good, this closing section is the best part. Christianity is inescapably trinitarian: God’s nature is fundamentally triune, and His relation to man, through creation, revelation, salvation and glorification, is an unavoidable expression of His triunity. Yet so often our life and worship is practically unitarian. Letham wants to see the church recover an essential trinitarian life and worship, and this God-glorifying focus is very refreshing. Letham develops how this appropriate focus on the trinity will have vital practical outworking in our salvation, sanctification, worship, prayer, evangelism, and sacrificial love for fellow believers with whom we are united to Jesus.
Letham encourages us to see the trinity as expressed through all of reality, and to enjoy unity in diversity and diversity in unity. This contrasts on the one hand with postmodernism’s diversity without unity, and on the other hand Islam’s unity without diversity. Only Trinitarianism can understand a reality that is both united and diverse. (This echoes Van Til’s apologetic emphasis on the problem of the one and the many, to which only Trinitarian Christianity has an answer.)
It seems to me that an appropriate focus on the gospel must result in an appropriate understanding and focus on the trinity. Even more clearly than in creation, the gospel showcases both the unified and diverse act of God in saving us. Each person of the trinity plays a distinct role in our salvation, but the unity of God’s purpose and action in saving us is also clear.
Following are several quotes that struck me while reading this book:
Quoting Gregory Nazianzen, Oration on Holy Baptism:
This I give you to share, and to defend all your life, the one Godhead and power, found in the three in unity, and comprising the three separately; not unequal, in substances or natures, neither increased nor diminished by superiorities or inferiorities; in every respect equal, in every respect the same; just as the beauty and the greatness of the heavens is one; the infinite conjunction of three infinite ones, each God when considered in himself; as the Father, so the Son; as the Son, so the Holy Spirit; the three one God when contemplated together; each God because consubstantial; one God because of the monarchia. No sooner do I conceive of the one than I am illumined by the splendour of the three; no sooner do I distinguish them than I am carried back to the one. When I think of any one of the three I think of him as the whole, and my eyes are filled, and the greater part of what I am thinking escapes me. I cannot grasp the greatness of that one so as to attribute a greater greatness to the rest. When I contemplate the three together, I see but one torch, and cannot divide or measure out the undivided light.
On the filioque and Jesus’ eternal submission (but not subordination) to the Father (p. 401), reminding us that God is who He has objectively revealed Himself to be:
The economic Trinity is a reliable gauge of the immanent trinity, owing to the faithfulness of God [emphasis mine]. [Quoting Jurgen Moltmann], “One cannot say, therefore, that something holds true in God’s revelation, but not in God’s being.”
Quoting Sergius Bulgakov, The Orthodox Church:
The dogma of the Holy Trinity is not only a doctrinal form, but a loving Christian experience which is constantly developing; it is a fact of the Christian life. For life in Christ unites with the Holy Trinity, gives a knowledge of the Father’s love and the gifts of the Holy Spirit. There is no truly Christian life, apart from knowledge of the Trinity; this is abundantly witnessed in Christian literature.