This Festschrift in honour of Werner G. Jeanrond, currently Master of St Benet’s Hall, University of Oxford, UK, investigates the challenge of alterity for Christianity, exploring and elaborating on this core concern in Jeanrond’s hermeneutical theology. Blurring disciplinary boundaries, more than thirty of Jeanrond’s colleagues and companions from ten countries track the dynamics of difference driven by the encounter with the self as other, the other as other, and God as the radical other. Who is my other? What do I encounter when I encounter my other? And what responses and responsibilities does the encounter with my other evoke? Grappling with questions like these, the contributions to this compilation analyse alterity in the Bible, alterity in philosophy, alterity in theology, alterity in interreligious dialogues, and the radical alterity of God. Tying in with Jeanrond’s explorations of the many faces and facets of the other, this Festschrift ultimately aims to advocate openness to the other as a necessity for both religion and reflections on religion.