Ecclesiology is a part of systematic theology which is studying about church. Churches in this era has been developed and shaped in many forms. Obviously the churches tend to build their own authority and kingdom. In this article, describing about how important as church to be Christ centered and realize their main obligation to spread the Gospel as Missio Dei (mission from God). The method that been used is historical approach as shown in the scripture, specially the Book of Acts. The challenge that has been found recently is that the church should keep on working among people in post modern era through contextualization mission. People has their own beliefs and what we can do is becoming part of the world with new paradigm as God view to establish His Kingdom as in heaven and earth. The summary said that church should not focusing inside only but should keep doing outreach to all over the world. The church should be Christ centered and mission centered as living organism. The church is a movement that happen continually and progressive.