Three decades after his untimely death, the theological and ecumenical legacy of Nikos Nissiotis remains unprecedented and undiscovered. At a time when global society and Christianity face unforeseen challenges in society and politics, science and technology, as well as the rise of religious nationalism and radicalism, Nissiotis’ theological voice, founded on the spirit of dialogue, offers a vibrant interpretation of Church teaching as well as a timely reflection on ecumenical relations.Nikos Nissiotis served for many years as Director of the Ecumenical Institute in Bossey and was the Orthodox voice in the World Council of Churches in Geneva. In ecumenical conferences throughout the world, he was capable of communicating the Orthodox response to questions of common interest in a clear, coherent, and comprehensible manner. We miss this extraordinary Greek theologian in the global dialogue of Christianity, and we will never forget his theology of “paschal joy.”