The doctrine of the Trinity is one of the most distinguishing marks of Christian faith. This is the first book to present an overview of the role of the Trinity in Christian theology in relation to religious pluralism and other religions. Approaching the study of the relationship between Christianity and other religions from the perspective of the Trinity, this book surveys all the major contributions to the topic by leading theologians at the international and ecumenical level. Veli-Matti Karkkainen points to future challenges and areas in need of development, examining in detail a case study exploring how the Catholic Church has responded to Islam from the perspective of the Trinity. Students of theology and religious studies will find this an invaluable text for courses that discuss religious pluralism and Christianity's relation to other religions. Pastors, other Christian workers, and academics will also find it a handy reference tool for teaching and further study.