Indonesia is known for its multicultural social setting, with approximately three hundred local ethnicities and five hundred local languages. Religions also have infiltrated into the life of Indonesia. Among six officially recognized religions, Islam occupies the majority religion in the country, and the total number of Muslims is almost two hundred million. That makes Indonesia the most populous Muslim country in the world. However, we also know that the legacy of pre-Islamic civilizations, such as Hinduism, Buddhism, and indigenous religions, is still deeply rooted in Indonesian soil. With this socio-cultural background, Indonesian Islam has developed with the influence of local traditions. We see several Islamic rituals and practices that seem to have been "Indonesianized". Yet, this localized version of Islam is by no means favoured by more religiously strict Islamic groups. In 2015, Nahdlatul Ulama, the largest Islamic organization, launched the so-called Islam Nusantara movement, which upholds the essence of local culture in Islam. This newly-emerged religious movement also presents a profound question in relation to the authenticity of religion, that is, whether religions are able to maintain the "original" rituals and practices without historical, geographical and regional influences. We will explore the development of the Islam Nusantara movement with this question in mind.
