This book attempts to explain the main features and developments of the three monotheistic religions. Though it treats nothing in depth, it gives good summaries of some points and provides tantalizing details which might be new even for people with some knowledge of the subjects. It is copiously footnoted and readers are encouraged to examine the listed sources for more detail.
Of course, being a broad survey, it does contain errors and questionable simplifications, some more serious than others. This isn't the place to get into all of those, but a couple points could be mentioned.
First Esposito noted the timeliness of this book in its foreword: inter-religious understanding is now more important than ever. Regrettably some opportunities to clear up misunderstandings were missed. Pp. 114-115, for example discusses martyrs, noting that Husayn, grandson of Mohammed, is the prototypical martyr of Islam. The Shiites see it that way, but do Sunnis also recognize Husayn as the prototype of a martyr? That's new for me. But when I read of Islamic martyrs, I think of Yasser Arafat , who called suicide bombings martyrdom operations. Peters had a good chance here to clarify the notion of martyrdom in Islam, but he didn't. So the question remains, at least for me: How do real Muslim scholars define a martyr?
Perhaps the most flagrant evasion of an issue is the discussion of Muslim asceticism, which follows a rebuke of Christian mortifications, esp. pp. 118 and 121. When the subject turns to Mohammed, he is seen as being more balanced. "He seems neither excessive nor particularly abstemious in his behavior. ... Nor did he preach to others any discernible degree of voluntary self-restraint or self-denial with respect to the legitimate pleasures in life (p. 121)."
I don't think one can fairly discuss Christian asceticism without mentioning the virtue of chastity. Christians are taught that their bodies are God's temple, God's spirit dwells in them, they are members of Christ's body, and non-marital sex is a sin against one's body (I Cor. 3:16, 6:13-20). Jesus also states that sexual sins can be committed in the heart, just by lusting for a woman (Matt. 5:28). This kind of asceticism or self-restraint is expected of all Christians.
But back to Mohammed. What were these "legitimate pleasures in life" which he allowed? Well, Muslim men could have sex with their slaves (Quran, 33:50-52, wrongly given by Peters (p. 121) as 35:50-52), and by extension with their female prisoners of war. Thus Bukhari 005:059:459, Muslim 008:3371 and numerous other ahadith show that Mohammed's men practiced coitus interruptus on their prisoners because a pregnancy would lower their value on the slave market. Mohammed mildly rebuked the interruptus, but not the coitus. Of course nearly all sex with war captives was non-consensual, or put another way, what Peters calls "the legitimate pleasures in life" included the rape of women at the mercy of Mohammed and his troops.
So, when Peters talks about the "self-abasement" of overzealous monks in the desert (p. 118), probably due to a strong Manichaean influence, he is ducking a larger issue. Christian chastity makes it possible for us to treat ourselves and all people, regardless of their background or circumstances, as created in the image of God. In the eyes of a Christian, Mohammed's troops not only abused and abased their victims, they also defiled themselves. This is not a mere difference of degree, with Mohammed being more easy-going than Paul in matters of sexuality. Radically opposing viewpoints on human dignity and personal sanctity come to the surface in this and in other incidents.
My question about this book, therefore, is whether certain facts are being ignored to spare people the pain of having to confront some unpleasant truths. Admittedly this works both ways. I was happy to read a book on this period without having my face rubbed in the atrocities of the First Crusade again. But if we are to make progress in understanding one another, and bettering ourselves, we must also undergo the afflictive process of confronting the crimes which are sadly part of our heritage.