What makes a church the church? This question has been well answered in the Lutheran tradition. However, as the living em- bodiment of Christ‘s promised Word and grace, we must cons- tantly reflect on what the church‘s existence means and how it relates to the contemporary world. We investigate this subject by comparing the ecclesiologies of Helmut Thielicke and Paul Tillich. Their theologies have their roots in the Lutheran her - itage, but they built their ecclesiologies respectively upon the Christocentric and Pneumatological approaches. Throughout the study, we affirm that a comprehensive understanding of “what is the church?“ should have an inclusion of its spiritu - al, essential, invisible essence and its social, existential, visible embodiment. Starting from this ontological basis, we discuss several ecclesiological issues, including the ecclesia-social rela- tionship and participation, the church‘s role as a salvation me- diation, and a good ecclesiological approach to the ecumenical movement. As well as this, in the light of the traditional notions of the church‘s four marks, the difference between Thielicke‘s and Tillich‘s approach is highlighted; and from which we con- sider whether an ecclesiology with the characteristics that uni- versality overwhelms distinctiveness is advisableweiterlesen