Ecumenism! It instantly brings to mind the sometimes confusing activities of Christian churches in the last century. But ecumenism is more ancient and has widespread roots-an approach to the transcendent realities of life without hostility or fear of syncretism. Both international relations and interreligious rivalry can offer a rationale for war and conflict. The warrior-physical or spiritual-is greatly to be admired and honored, but ultimately our hope rests in the ecumenist. The statesman may enforce peace by external means; but the ecumenist mindful of the psalmist, "were I to give a burnt offering, you would not be pleased. The sacrifice acceptable to God is a broken spirit..." must strive to elicit an interior human act. The Theology of Ecumenism examines ecumenism with a theological vision as well as from aspects based on our human nature. Given the current strains between Islam and Christians it offers a guide-seeing ecumenism as central to our relationship to God and to our relationship with every human being as an "image of God." Antoninus Wall is uniquely qualified to write on this subject. He was instrumental in bringing the Catholic presence to the Graduate Theological Union in Berkeley and served as a professor and president of the Dominican school there.