As a strategy of the political culture, religious assimilation constructed in New Order has become a concept which is considered uneffective and failure. The Post-reformation era has become the sign of the failure of the concept of religous assimilation. The policy of the religious assimilation which is disigned for reducing conflicts between ‘Pribumi vs Tionghoa’. In fact, it has sharpenned and deepened the gaps between the two groups. Religious conversion by the Chiness in terms of assimilationism of new order turns to be a political strategy to describe and to have the pribumi identity which is considered as the majority and muslim. In this case, everyone can claim their own identity and say “who I am”, “who you are”, and “who we are”. In the future, for the agenda of assimilation, religious conversion will loose it’s the relevance. It is see that the process of assimilation appears from social engeneering that separates the differences of cultural roots of ‘Tionghoa-Pribumi’ while the contestation of culture in area of multiculturalism reunites the entity of diversity into the singgel identity. Therefore, the celebration of Chines New Year (IMLEK) in mosques in Yogyakarta becomes a form of integration of identity between Tionghoa-Islam and Java.