Not by Paul Alone explores the historical reasons for the creation of the book of James and the implications for the creation of the Christian canon. Nienhuis makes a compelling case that James was written in the mid-second century and is, like 2 Peter, an attempt to provide a distinctive shape to the emerging New Testament. This book bolsters the claim that the Catholic Epistles not only have a distinct witness individually, but that collectively they are also a considered theological agenda within the Christian church.
I don't agree with his premise about James or much of his historical reconfiguration. But he does a great job showing that the Catholic Epistles are a unified whole.