Start with the warning that readers' eternal souls are at stake if they are wrong about the Trinity, and follow that up (on the same page if possible) with the admission that nobody can understand the doctrine anyway.
Then jump into a concordance-like review of the biblical evidence, starting with the Old Testament and emphasizing the most ambiguous elements of it (the plural form of Elohim, the "let us make" statements, the threefold repetition of "Holy"). Insist that these have the value of proofs.
Move quickly through the New Testament's main story, lingering only at the triadic formulas, and then camp out in the statements of the ecumenical councils and church fathers, giving the impression that everything was unclear until smart people got creative in the fourth century.
Insist that majority ruled at Nicaea, so we should follow that.
Suggest that everybody had forgotten about the Trinity until your book came along, and finish off with a generous exploration of all kinds of analogies for the Trinity (iceberg, shamrock, apple, egg) before admitting that all analogies are kind of limited.
None of the Trinity books on my shelf are quite that bad. Not one of them commits every error! Nevertheless, these weaknesses are pervasive in the "popular Trinity book" genre.
This is in the context of reviewing a popular introduction to the doctrine: Philip Ryken and Michael LeFebvre's Our Triune God: Living in the Love of the Three-In-One, which Sanders likes very much.
The good news---and what makes Our Triune God the best book to put in somebody's hands if they're asking for an introduction to the doctrine---is that Ryken and Lefebvre simply leapfrog over all those errors as if they never existed, and get down to the serious business of teaching the Trinity the right way. What constitutes "the right way?" Two things stand out: Ryken and Lefbvre's presentation is biblical and gospel centered.
He concludes the review in this way:
This modest little book is a sign of great hope: the new normal in how evangelicals approach the doctrine of the Trinity. Apparently there is such a thing as evangelical trinitarianism: biblically articulate, gospel centered, and unharassed by side issues. It's small and accessible; get it into as many hands as you can.
You can read the whole thing here.