Monotheism and Its Complexities

Christian and Muslim Perspectives

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Lucinda Mosher, David Marshall
  • Washington, DC: 
    Georgetown University Press
    , July
     208 pages.
     For other formats: Link to Publisher's Website.


Superficially, it may seem that Muslims have a simple belief in one God while Christians complicate matters with the Trinity. Lucinda Mosher and David Marshall’s Monotheism and Its Complexities, however, demonstrates that for both Muslims and Christians affirming the unity of God raises complex theological challenges, and that the number of gods they believe in is not what divides them.

The volume reports on the 15th annual Building Bridges seminar in 2016, which brought together international Muslim and Christian scholars to explore “the most significant themes in the interface between Islam and Christianity” ( The preface provides a retrospective of the first decade and a half of the seminar, describing its methodology (“relational theological exchange”), history, impact, and future.

As in previously published proceedings, papers and responses alternate between Muslim and Christian scholars, followed by selections of scriptural and theological texts, which were discussed in small group sessions. The volume ends with a report on the small group conversations, and a comprehensive index.

The first two parts concern the oneness of God in scriptural sources. Richard Bauckham portrays the Old Testament as monotheizing literature, developing only gradually into the strict monotheism of Judaism. The New Testament complexifies this monotheism by allowing for God to share the divine eternal life with humans through Jesus and the Spirit, leading to the later fully articulated Christian doctrine of God as a Trinity. In her Muslim response, Maria Massi Dakake notes that, in contrast to Christianity, Jesus in Islam is firmly placed on the human side of the chasm between divine and human. Both traditions attempt to bridge the chasm, Christians through the limitation of human flesh (the incarnate Christ) and Muslims through the limitation of human language (the Qur’an).

Asma Afsaruddin’s explicates the centrality of the belief in monotheism (tawḥīd) in the Qur’an and its critique of imputing fatherhood or the number “three” to God (although she raises the possibility that the latter is a condemnation of heterodox tritheism not orthodox trinitarianism). Islam, however, has its own theological challenges in reconciling the unity and uniqueness of God with God’s names and attributes (which imply multiplicity) and with the Qur’an’s anthropomorphic descriptions of God (which associate God with human limitations).

In his Christian response, Sidney Griffith warns against dissolving the differences between Muslims and Christians in facing the theological task of monotheism. He notes how the Qur’an reformulates trinitarian language to construct its own Christology, wherein Jesus is a messenger of God, God’s word, and a spirit from God (Qur’an 4:171), and explicitly repudiates the Christian claim that Jesus is “son of God.”

The third and fourth parts concern the centuries of theological labor by Christians and Muslims of grappling with the doctrine of God’s unity. Christian Schwöbel provides an overview of Christian trinitarian discourse from its grammatical foundation in scripture and worship through its successive elaborations by early church theologians, creeds and councils, medieval debates, Reformation and Enlightenment formulations, and modern philosophical and ecumenical understandings. Rather than an ever more complex explication of Trinitarianism, he characterizes this history as a “radicalization of monotheism in which monotheism is ultimately grounded in the triune self-manifestation of God” (87).

Martin Nguyen’s Muslim response helpfully depicts the history of trinitarian discourse as storytelling, in which “we humans, in our finitude . . . waver and struggle to see what is precisely happening in the Godhead” (94), the complexities of which are not lost on Muslim theologians who struggle with God’s attributes, actions and names, and with the opposing binaries of appearance versus the real, and of transcendence versus immanence.

Sajjad Rizvi’s essay lays out the main contours of Muslim theological and philosophical exploration of what it means to say that God is absolutely one and other (including denying the numerical sense of “one” as applicable to God). God is both transcendent and immanent. God’s transcendence raises the problem of the relationship of the divine essence to God’s names and attributes, to the Qur’an as God’s word (created or uncreated?), and to God’s knowledge of particulars and God’s agency in human history. As imminent, God is present for believers, which finds its highest experience in the annihilation (fanā‘) of ego in tawḥīd, indicating that within Islamic monotheism lies the kernel of monism (God alone really exists).

The Christian response by Janet Soskice, expresses appreciation for the various complex stories of monotheism in Islam and Christianity, but finds a unity, shared with Judaism, in the notion of divine creation ex nihilo. Humans cannot grasp what God is, in and of herself, but they can know who God is for them.

Lucinda Moser’s concluding report on the actual conversations during the small group discussions stands out for the quality and honesty of the conversations and the carefulness and professionalism whereby they are reported.

This volume demonstrates the advantage of doing interreligious theology. The respectful interplay between Muslim and Christian scholars highlights the challenge and creativity evoked by the experience of the relationality of the divine vis-à-vis abstract notions of monotheism, and the limitations of temporally and linguistically bound humans in penetrating divine being beyond these limitations. This reviewer also appreciated the use of The Study Qur’an by Afsaruddin, and Rizvi’s use of both male and female pronouns to refer to God.

The main critique of the papers in this volume is the proclivity for discussion of abstract notions in a vacuum devoid of the social, political and economic contexts of the actors. Even the influence of each tradition on the other’s development of monotheistic discourse (especially within the creative matrix of Late Antiquity) is seldom engaged, notwithstanding gestures such as Schwöbel’s reference to Thomas Aquinas’ intellectual engagement with the thought of the Muslim Ibn Sina and the Jewish Moses Maimonides (86).

Nonetheless, this is an impressive work of interreligious theological dialogue. Be assured that at least here Muslims and Christians engage each other seriously and hospitably without ignoring their differences but make them the basis of a life giving and affirming dialogue.

About the Reviewer(s): 

Franz Volker Greifenhagen is Professor of Religious Studies at Luther College, University of Regina, Saskatchewan, Canada.

Date of Review: 
January 15, 2021
About the Author(s)/Editor(s)/Translator(s): 

Lucinda Mosher is Assistant Academic Director of the Building Bridges Seminar; Faculty Associate in Interfaith Studies, Hartford Seminary; and Center for Anglican Communion Studies Fellow in World Anglicanism, Virginia Theological Seminary, Alexandria, Virginia.

David Marshall is Academic Director of the Building Bridges Seminar; Senior Research Fellow of the Berkley Center for Religion, Peace, and World Affairs; and Associate Professor in the Theology Faculty of Georgetown University, Washington, DC.


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