This study examines the W.C. theological thought of W.C.C. with the question of church unity and intends to reach a rational conclusion in light of Calvin s theological thought. The purpose of this study is to establish the theories of correct church unity through the criticism of W.C.C.. Considering the discussion of W.C.C. in Korean churches, it was very superficial in the controversy over W.C.C. s whole church, and as a result W.C.C. It was a factor that prevented the problem from being resolved reasonably. Especially, in the Korean situation, liberalism and religious pluralism are very difficult issues for Korean conservative church to accept. For a desirable church, First, we need to recognize that the Church of Christ is a church.\nSecond, we must acknowledge the existing common church reality. Third, the commonalities with other churches should be realized in their churches from the perspective of other churches. Fourth, do not sacrifice truth. In conclusion, good church unity has nothing to do with global institutional integration as claimed by the W.C.C. and can only be achieved when the unity of faith, the unity of church essence, and the principle of non-divisibility principles are applied.