You can read the full review of Margins of Islam here.

Review by Mark Pickett - Mark Pickett works with UFM Worldwide, teaching cross-cultural ministry in face-to-face settings and online at http://infusion.global. He has ministry experience in South Asia and the UK.

And here are selected quotes from the book review:

• Most books about Islam, by Muslims as well as by evangelicals, describe normative or classical Islam and might be called “Islam from above”. Such books are not wrong. They are just inadequate to explain the huge variety of expressions of Islam one actually finds around the world.
• The approach of the contributors to this book is to look at Islam from below…
• In our day, an unprecedented number of Muslims are coming to Christ. This tremendous answer to prayer should not leave us complacent, however, as the number of Muslims in the world grows by thirty-two million per year, mainly through high birth rates (204). So, the challenge of engaging the Muslim world with the gospel of the Lord Jesus Christ is undiminished.
• One of the editors of Margins of Islam, Warrick Farah, argues that, “Islam is perhaps the greatest challenge the church has ever faced. Yet it is not simply that we do not know the answers; we are also unsure of the nature of the problem” (205). As we have seen in politics, so also in making disciples. This slim volume, written by seventeen reflective practitioners with significant experience of a wide variety of Muslim contexts, is a major contribution to examining that problem….
• The central concern of the book is, quite simply, to aid cross-cultural workers seeking to communicate the gospel to Muslims by helping them to understand Islam better. Consider it an exploration of the following questions: what is Islam, who is a Muslim, and what difference does it make?
• Paraphrasing the work of Shahab Ahmed, Farah defines Islam as “a process of ‘meaning-making’ undertaken by Muslims as they interact in their context with the revelation given to Muhammad” (14).[9] He goes on to propose that we consider viewing Islam as “one strand in the braided rope of society” (18, original emphasis), a model that makes so much sense when one reads the case studies.
• Reviewing his own ministry journey, Farah suggests that the braided rope analogy has aided him in forming a missiological understanding.
• I assumed Muslims believed the things I thought Islam taught. But when I started to listen and enter the challenge of exploring my Muslim friends’ faith, I discovered that the search for true Islam was not only illusive but also irrelevant. Instead, I decided to build my understanding of Islam on my friend’s understanding because that is what Islam was to him, and in the context of genuine dialogue and witness that is what is most important. (19)…
• Farah argues against an essentialist view of Islam. Such a view, he argues, rightly in my view, is a product of the Orientalist movement in scholarship, that emerged in the nineteenth century (196-99). While the editors, at least, want to shun essentialism, they do accept that there are boundaries. Though they do not say so, it would seem that they prefer to view religions as, in Paul Hiebert’s terminology, centred sets rather than bounded sets.[19] Farah wants not only to avoid the false objectivity of a modern approach but also the relativism of a postmodern one (198). Religion, then, is socially constructed – “it would not exist if there were no people” (199). For this reason, we “desperately need to be alert to how we use the category ‘religion’ in mission” (199). This is a vital discussion and, for me, is worth the price of the book.