The purpose of this paper is to examine the “Epistle Sent from the United Church of Christ in Japan to Christians in the Great East Asia Coprosperity Sphere” issued in 1944. This paper will survey the historical background and contents of the Epistle and compare its message with the theology of Karl Barth (1886-1968), which the Japanese theologians drew on to compose the Epistle. It will be argued that the Epistle, while adopting expressions and themes from Barth``s works, especially his commentary on Philippians, distorted Barth``s own theological and political intentions in order to serve Japan``s wartime policies. Theologically, the major factor that led the Japanese Church to her regrettable wartime compromises and sins was her lack of absolute obedience to the First Commandment. This case study illustrates how Reformed Life Theology, with its emphasis on the relevance of theology to life and faith, the lordship of Jesus Christ, and the service of theology to the world, can contribute to the important issue of the Church``s relationship to the state.