A friend of mine suggested my next book be Miroslav Volf's Allah: A Christian Response. In fact, he actually bought the book for me; thanks again, friend.
I think understanding this book starts with understanding the author. Volf's Wikipedia page carries a lot of noteworthy accomplishments and glowing references. Theologian, seminary professor, author, public intellectual, White House advisor . . . the man has a long and reputable résumé. There is a strong theme throughout his work, however, of interfaith engagement, the most relevant work being his crafting of the "Yale Response" to "A Common Word."
This book seems to have been an outgrowth of that work, though in this case, Volf's audience is fellow Christians, or at least that's what he claims in the book. The central question Volf seeks to answer in Allah is, "Do Christians and Muslims worship the same God?" Nabeel Qureshi answered the question in the negative. Volf, in the course of the book, says, "Yes, we do worship the same God." (If you're interested in hearing these two debate the matter, there's audio of just that.)
Volf spends a lot of time laying his groundwork, but his basic argument follows that of "A Common Word," arguing that Muslims and Christians worship the same God because of their common ground, a faith centered in the love of God and the love of neighbor. He spends a great deal of the book unpacking these ideas.
I really struggled to finish this book. My first inclination while reading it was to call Volf a hack. That isn't fair or charitable, but it was born out of irritation, and a sense, as I worked my way through the chapters, that Volf was not dealing with the topic in an honest manner. I can't know the process by which Volf reached the conclusions he did; I can't unpack the people he's met or the books he's read. However, I can at least respond to the arguments he's made, and they are not convincing, as far as I'm concerned.