Ali's work evaluates and compares biographies of Muhammad, ancient and modern, favorable and unfavorable, arguing that the emphases of these life histories reflect the concerns of the age in which they were written. Thus non-Muslim, seventeenth-century writers denounce Muhammad as a false prophet while twenty-first century authors focus on his intolerance. Meanwhile, contemporary Muslims hail him as the ideal businessman or consummate CEO—concepts that would never have occurred to earlier hagiographers.
For example, Ali shows how some of the most notable controversies that swirl around Muhammad in the modern era—particularly the question of Aisha's age at the time of her marriage to the prophet—did not even trouble those who earlier wrote negatively about him. These previous critics excoriated Muhammad for his lust or his dynastic scheming in marrying the daughters of all of his most important and powerful followers, but it was not until contemporary times that writers were troubled by what can be seen as pedophilia or, perhaps more importantly, whether his example encourages pedophilia and child marriage in the Muslim world today.
However, Ali's book is guilty of a grave defect: She is generally disdainful of biographies that are critical of Muhammad while dismissing legitimate concerns about the examples that stories about him set for contemporary Muslims. Her chief complaint, for example, about this author's own biography, The Truth about Muhammad, is that while it provides "reasonably accurate information," it is "framed and interpreted in relentlessly negative ways." Conversely, she characterizes authors of positive biographies such as Karen Armstrong and Tariq Ramadan as "public intellectuals"; this author, on the other hand, is described as a "professional polemicist" and the "grand pooh-bah of the legion of American Islamophobes."
Similarly, Ali's use of the propaganda neologism "Islamophobe" to tar Muhammad's critics mars the academic value of her work. Her preference for admirers of Muhammad frequently clouds her ability to evaluate the data. Writing of Armstrong's Muhammad: A Biography of the Prophet, Ali tells the reader that the author "describes Muhammad's actions, contextualizing them but without exculpating him." Without exculpating him? Her book includes the fanciful claim that "Muhammad eventually abjured violence and pursued a daring, inspired policy of nonviolence that was worthy of Gandhi," an assertion with no basis in Islamic texts.
The premise of The Lives of Muhammad is intriguing, and it contains a good deal of useful information. It is, however, marred by the author's failure to take seriously the numerous reasons why Muhammad is so deeply problematic a figure for non-Muslims and secular Muslims alike.
 Muhammad: A Prophet for Our Time (New York: HarperCollins, 2006).
 In the Footsteps of the Prophet: Lessons from the Life of Muhammad (Oxford: Oxford University Press, 2007).
 San Francisco: HarperOne, reprint ed., 1993.