The purpose of this study is to investigate the contextualization theology of M. M. Thomas which have been influenced World Council of Churches(WCC)`s theology. Tomas` methodology of theology can be divided into two. First, his theory is situational because he looks into the world and analyzes what is happening in the world and try to find the solution in christian way. Second, his theology is actionoriented. He insists that theology should interpret the truth of christ on the basis of the situation and do action according to that. And his christianity`s action divided into the world, people, community and history. Christianity`s actions need conversation with another religions, therefore christians need conversation with hinduism. This can lead to religion syncretism and pluralism. Tomas was the official member of WCC and placed emphasis on ``struggle of spirituality`` for righteous and humankind unite, aimed that christians and other religious people should be united and form culture community. He is open to all religions and ideology and claims religion syncretism based on ``personality of jesus christ``. Owing to Tomas, India`s pluralism and syncretism is wide spread in India, it helped India`s inclusion thought go over the church united movement and expand to the worldwide. Christianity doctrine`s ethicality and absoluteness was excluded and the truth of joint pursuit through the conversation and work of holy spirit or ``spirituality`` and the purpose of finding other religion`s ``Christ`` are requested based on India`s comprehensive religion syncretism and pluralism. This movements are the most serious challenge to mission work of modern christianity.