One of the very earliest recorded encounters between a Christian and a Muslim, a public debate between a Syriac patriarch and an Arab emir shortly after the Arab conquest of Syria, concerns the role of law in religion. Without a body of law, the emir insisted, Christianity could not call itself a religion; Christians should convert to Islam, a real religion that had the Sharia. The patriarch responded that Christians indeed had law, though not as Muslims understood it; Christians had no need to convert. I thought of this debate when I saw a notice for a forthcoming book from Cambridge, Law and the Rule of God: A Christian Engagement with Sharia, by Joshua Rallston (Edinburgh). Law–or, rather, the proper conception of law–is a major point of contention between these two world religions, and a comparative study like this one seems very promising. The publisher’s description follows:

Sharī’a is one of the most hotly contested and misunderstood concepts and practices in the world today. Debates about Islamic law and its relationship to secularism and Christianity have dominated political and theological discourse for centuries. Unfortunately, Western Christian theologians have failed to engage sufficiently with the challenges and questions raised by Islamic political theology, preferring instead to essentialize or dismiss it. In Law and the Rule of God, Joshua Ralston presents an innovative approach to Christian-Muslim dialogue. Eschewing both polemics and apologetics, he proposes a comparative framework for Christian engagement with Islamic debates on sharī’a. Ralston draws on a diverse range of thinkers from both traditions including Karl Barth, Ibn Taymiyya, Thomas Aquinas, and Mohammad al-Jabri. He offers an account of public law as a provisional and indirect witness to the divine rule of justice. He also demonstrates how this theology of public law deeply resonates with the Christian tradition and is also open to learning from and dialoguing with Islamic and secular conceptions of law, sovereignty, and justice.