A treasure trove of information. Morgan exhaustively surveys how the concept of pistis (which we typically translate as "faith" or "belief" in the New Testament) was used throughout the everyday culture of the ancient Greco-Roman world.
She effectively demonstrates her thesis that in the first century, pistis would have been widely understood as referring to an active relationship of trust rather than to an act of mental assent to ideas. Trust, loyalty, and faithfulness are thus generally better glosses for "faith" terminology in the New Testament in almost all of its uses, and any understanding of pistis as referring to a body of doctrine or the act of assenting to doctrine is anachronistic when it comes to biblical usage. It's a simple enough claim, and one I needed no additional convincing of, but after reading Morgan's book I feel as though I've gone from having a passing familiarity with this foreign word to being truly fluent with its full cultural import. It opens up a deeper conceptual world to the language. Morgan also helpfully elucidates passages like Romans 1:17, James 2:14-26. and references to pistis Christou (the "faith/faithfulness" of Christ).
Morgan's expertise is clear not only in the amount of primary sources she quotes, but also in the nuanced way she evaluates their use of language and her engagement with previous scholarship on the topic. Any serious student or scholar interested in how the Bible speaks about faith/trust will need to take this book into account. That said, it is VERY meaty and technical and thus also not for the faint of heart. Interested lay readers (particularly Christians interested in New Testament studies) can find a popular-level treatment that draws on many of Morgan's conclusions in Matthew Bates' Salvation by Allegiance Alone.