This compilation investigates the challenge of alterity for Christianity. Blurring disciplinary boundaries, more than 30 contributors from 10 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 analyse alterity in the Bible, alterity in philosophy, alterity in theology, alterity in interreligious dialogues, and the radical alterity of God. Ultimately, this compilation aims to advocate openness to the other as a necessity for both religion and reflections on religion.