One of the many faces of Islam in Indonesia is the abangan Muslims or the abangans. As one of the most populous Muslim groups in the country, it is important to know them. To understand Indonesian Islam or Muslims, one cannot overlook them. The article argues that, amid recent escalating Muslim–Christian tension in the country, this majority Muslim group can play a significant role in enhancing Muslim–Christian relations in the future, on account of their worldview that emphasizes and maintains cosmic (...) harmony and balance of all existence. Their open and syncretic attitudes toward other religions may foster religious tolerance and coexistence. These are attested in the author’s personal engagement with them. It is suggested that Christians be more inclusive toward them, but, at the same time, be critical in engaging their worldview. These attitudes are necessary for building a mutual and peaceful Muslim–Christian relationship in the region. (shrink)