Ecumenism in postwar Asia, institutionalized in the Christian Conference of Asia, displayed a remarkable this-worldliness from its inception in the 1940s. This tendency was in contrast to the tension between the church-centric and world-centric approaches to Christian mission that marked conciliar mission thinking in the West. This work examines the development of such this-worldly holiness in Asian ecumenism, focusing on M. M. Thomas of India and C. S. Song from Taiwan. Special attention is drawn to the idea of "God's this-worldly presence" that considers God as redemptively at work in world history apart from the church. The study first compares the development of this-worldly holiness in the West and Asia and then examines the thinking of Thomas and Song. The chapters on these two theologians discuss their backgrounds, the basic concerns motivating their intellectual searches, and responses to the questions arising from such concerns. These chapters also try to understand how these theologians view the relationship between God and the world. In so doing, the study highlights the significance of the idea of God's this-worldly presence shared by Thomas and Song in spite of differences in their backgrounds, approaches, and theological formulations. Having compared Thomas and Song, the study concludes that the idea of God's this-worldly presence became central to Asian ecumenism because it offered a common unifying vision to Asian Christians who come from a region characterized by tremendous diversity. The idea helped them to see the diverse peoples, cultures, and religions in Asia under one God who transcends the diversity and still takes it seriously.