John Renard's study, Islam and Christianity: Theological Themes in Comparative Perspective, should be welcomed by students of Muslim–Christian relations as a unique contribution to the field. Perhaps the book is best suited to intellectuals belonging to either Christian or Islamic traditions who are seeking fertile ground for cultivating rapprochement.

One might be well served by reading the epilogue first, which expresses the intent of the book: to address a desparate need “to step momentarily outside of our theological structures, not to consign them to the … blender of relativism, but to see ourselves on an equal footing with all other believing human beings” (p. 224). The text is a serious study that resists simple generalizations in comparing theology in Christianity and Islam.

The text offers many comparisons between Christian and Islamic theologies that Renard has gleaned from his “forty-year encounter with the sources of Islamic tradition” (p. 229) as both scholar and ordained Jesuit priest. Many of the book's insights echo categories and examples that Renard has already tested in his primer on Islam seventeen years ago, Seven Doors to Islam (and his more recent Friends of God (2008)), but now they are aligned in creative tension with evidence from his analysis of the Christian tradition. His project brings to mind the works of other churchmen in the field, from Louis Massignon to Kenneth Cragg (and, as Renard highlights, Richard J. McCarthy, SJ), whose efforts to understand Islam summon them to rich reconsideration of their Christian faith. One of the book's deepest strengths is its adherence to the languages of Christianity and Islam in Renard's quest to “combine the two streams of study” (p. xii) that have defined his life's work. He manages to combine these streams without co-mingling or losing the identity of either tradition.

The book is descriptive, aiming to describe the development of the Christian and Islamic traditions in ways that are recognized as authentic by scholars within each tradition, but along parallel lines. To see the traditions in parallel, the book is organized according to an evolutionary growth process that Renard claims to be exhibited both by Christianity and Islam – a process that has its genesis in “an evolving master story” that is expressed in “prime narratives that enshrine the earliest summaries of the core teachings of the faith” (p. 72). Chapter 1 describes origins of these narratives in Christianity and Islam (scriptures and exegesis). Chapter 2 presents thumbnail histories of the two traditions to highlight some parallel themes (most notably, apocalypticism) and orientations that can be found historically among both Christians and Muslims: 1) Idealism: clinging to the period of narrative origins as the “golden age” (p. 66); 2) Traditionalism: a “less selective … generally uncritical orientation” (p. 66) that finds inspiration in all periods of the faith's history; 3) Realism: a “pragmatic, modernist” orientation that emphasizes interpreting “The Revealer” in the historical context that the Revealer revealed the revelation; and 4) Personalism: an orientation focused on a personality, (e.g., Christian religious orders and Islamic Shiism). Chapter 3 describes the evolution from stories to creeds (such as the Apostle's Creed and the Fiqh Akbar I). Chapter 4 examines the rise of theology and splintering into theological schools (“though Christians and Muslims alike have long cherished the abstract notion of the ‘unity of all believers,’ the histories of both communities reveal at least as much evidence of pluralism as of uniformity” (p. 108)). Chapter 5 discusses the rise of authority structures in the two traditions (canon law and Sharī‘a). Chapter 6 describes the religious and educational institutions (even physical architecture), and political customs of both traditions. Chapter 7 shows how Christians and Muslims have tended to read sacred texts for moral guidance. Chapter 8 describes how Christians and Muslims respectively find inspiration in the Bible and the Quran, in the personalities of Jesus and Muhammad, and in “perhaps thousands … of exemplary figures” (p. 192) portrayed in Christian and Muslim hagiography. Chapter 9 provides many poetical examples from each tradition to show that “Christian and Islamic traditions of spirituality include some of the loveliest prayers that have ever graced the human voice” (p. 220).

While this summary portrays the book as descriptive, the underlying argument – that Christian and Islamic traditions evolved in parallel ways – gently unfolds through detailed analogies, comparisons, and contrasts. For example, by explaining some “shared … basic presuppositions about God and humanity” (p. 91) Renard argues that “a Christian attending services on Sunday could conceivably share more in his or her personal experience of God with a Muslim stranger who worships on Friday across town than with fellow Christians” (p. 90). Renard shows that despite acute differences between Islamic and Christian doctrine on matters of the Trinity and status of Jesus Christ, on a foundational level the two traditions affirm: 1) the need for divine assistance; 2) God's “active engagement in human history”; 3) the human tendency to “reject the divine initiative”; 4) that “divine disclosure is a process”; and 5) “there is a temporal limit to ‘formal revelation’” (p. 91).

A book of this scope exposes itself to criticism from many angles, but it will fare well under the scrutiny of many. The evolutionary paradigm is certainly modernist, but also aptly analogous with New Testament and Quranic notions of God's work in history. The book is regrettably inaccessible as an undergraduate primer, while sometimes tediously laden with definitions unnecessary for those advanced students of theology (in an uneven way: e.g., the book defines “ecclesiology” (p. 50) and “bishop” (p. 115), but not “shahada” (p. 84)). But Renard apologizes for this (p. xi); moreover, readership in Muslim–Christian relations is naturally uneven in its knowledge of either tradition, and the book is especially commendable for avoiding reductionism. One could also ask that the text give more attention to Middle Eastern Christians. For instance, why not mention Ephraem the Syrian (d. 373) in the list of Christian theological poets, considering his proximity to the Semitic milieu (p. 77)? Likewise, chapter 4 could be fruitfully augmented with an examination of the Arab Christian practice of kalām in the Islamic milieu. But such is the work for another book.