The paper examines the tension amongst the Indonesian government and Islamic organisations in dealing with the plurality of interpretation within Islamic tradition and at the same time maintaining the unity and harmony of the Muslim ummah. I provide two case studies here: first, the issue of determining the first and the end of Ramadan and also 10 Zul Hijjah (for Idu al-Adha). Second, who has the authority to issue halal certificate? Due to different methods of hisab (astronomical calculation) and ru’yah (sighting a new crescent), Islamic organisations (Muhammadiyah, Nahdlatul Ulama and Majelis Ulama Indonesia) have produced different fatwas. At the same time, the Government has to make announcement on which dates to begin or to end fasting. With regard to the second issue, there is currently a tension between the Government and the MUI as the first thinks it falls into its authority whereas the latter insists that halal certificate is a written fatwa which belongs to its 'jurisdiction'.The questions are: how does the government decide which fatwa to choose, and what are the reactions of Islamic organisations when their views differ with the position of the government? There is also tension in society in celebrating Idul Fitri and Idul Adha on different dates. How far should the government go to accommodate such different views, to maintain harmony in the community?