Indonesia is the most populous Muslim nation in the world with approximately 240 million followers of Islam. At the end of World War II, which simultaneously marked the end of colonisation, the future polity of Indonesia became the central issue to discuss. The then leader Sukarno and other national figures, including several Muslims, decided to establish a republic rather than a syariah-based Islamic country. This political decision was furiously rejected by some Muslims, as they believed that it was by no means in accordance with genuine Islamic teachings. In Indonesian modern religio-political history, we have seen arguments, disagreements, and even conflicts, in relation to the purity of Islam and the implementation of syariah among Muslims. The Indonesian Islamic community (umat) has never been amicable at least in the post-colonial era. There have been mutual criticisms and denial when discussing the political course of the country and the adaptation of local cultural traditions in Islamic practices. At the same time, although genuine Salafists never justify barbaric actions, such as indiscriminate killings, some militant Muslims who have wrongly interpreted the teachings of Islam have perpetrated terrorism. As a result, some non-Muslims confuse Salafists with terrorists, which could contribute to the creation of a negative stereotype of Muslims. The author of this paper will attempt to depict these discrepancies and diversities among Muslims in relation to their attitudes towards non-Islamic faiths and the polity of Indonesia based on field research. Furthermore, the author intends to explore the possible role of these diversities in the umat in preventing terrorism and in deradicalizing former terrorists in the paper.