I am glad there is a new interest in the Trinity among the Evangelical world. Like most things, the current revival of interest in the Trinity among Evangelicals reflects the increased academic interest in the trinity over the last 50-60 years (Barth, Rahner, Grentz, etc.).
What I find odd about the renewal of interest in the Trinity among Evangelicals is that they seem to want to not talk about recent academic writing about the Trinity.
So when I read Ryken’s book on the Trinity he wanted to talk about the Trinity as a purely individualistic issue and ignored the Trinity as a social theology (which has been the primary focus of modern Trinitarian writing.) Ryken also primarily seemed to talk about the Trinity not as who God is, but what the Trinity means to who we are as Christians (why we need the Trinity for salvation).
Sanders does not fall into quite the same problems. He explicitly says, “We have seen that God is triune at the deepest level, at the level of who he essentially is rather than merely at the level of what he does.” and later “God is Trinity primarily for himself and only secondarily for us. One of the consequences of this is that the Father has always been the Father, the Son has always been the Son, and the Holy Spirit has always been the Holy Spirit.”
Primarily Sander’s point in this book is that a weak theology of the Trinity leads to a weak Christianity.
“A gospel which is only about the moment of conversion but does not extend to every moment of life in Christ is too small. A gospel that gets your sins forgiven but offers no power for transformation is too small. A gospel that isolates one of the benefits of union with Christ and ignores all the others is too small. A gospel that must be measured by your own moral conduct, social conscience, or religious experience is too small. A gospel that rearranges the components of your life but does not put you personally in the presence of God is too small.
So I fully support the basic thesis, that the Trinity is important to Christian faith and that we need a deep meaning of the Trinity to have a deep understanding of our relationship to God.
My problem with the book, and why I got frustrated enough that I have given up on the book for now, is that Sander’s method of reintroducing the Trinity to the Evangelical world is to only talk about how Evangelicals understand the Trinity. Sanders wants to show that Evangelicals actually have a deep understanding of Trinitarian theology even if they have forgotten that they have a deep understanding of Trinitarian theology. So he explicitly decides to only quote Evangelical authors which means that with very few exceptions his quotations are Puritan or at least post-reformation.
That is not to say that Puritans and other post-reformation authors are not important. But you simply cannot talk about the Trinity and ignore the rest of the church. Trinitarian theology primarily is a development of the first 600 years of the church with minor revisions as the theological implications of philosophy get more developed over time. Even the implications of the social aspects of the Trinity that has been so developed over the past century is not completely new.
The Evangelical church cannot be the church and ignore the Christian world outside the Evangelical church. I am not saying that Evangelicals cannot have distictives in their theology. They do. But it is an active hinderence to Evangelical Theology to not know anything about the theology of the rest of the Christian church. That is why I specfically try to read theological works outside of the Evangelical world that I was raised in and trained in.
Overall I have been very frustrated in the looks into the Trinity as my reading project this year. Other than the very good book by Dunzl on the early History of the Trinity the books I have read have been ones that I would suggest you skip. Yesterday, (and the reason I finally gave up on this book) a new book on the Trinity was released by IVP in kindle format. Michael Reeves Delighting in the Trinity: An Introduction to the Christian Faith (Bookwi.se Review) has been very well reviewed so far. So I am going to start that. If that goes badly, then I am going to have to just start reading the academic books by Rahner, Grentz, Moltmann and Volf and others and give up on the popular level Evangelically focused Trinitarian books. (The problem is that I am afraid I am not smart enough to get them and I know most of them are expensive and/or not on kindle.)