It can be denied that Islam is one because all of Muslim around the world bear witness that there is no gods except Allah and Muhammad is His messenger, and they believe Koran as their holy book and their guidance. So, Normatively, Islam is one because its teachings come from the same sources –Allah. But, how Islamic teachings implemented factually? Do Muslim around the world have the same way in implementing it?

The answer, there are the same and some are not. The similarity is because Islam has values of universality. Its teachings could be implemented anywhere –even the geography and the culture are different- and timeless such as prayer five time in a day. Muslim around the worlds agree that the mandatory prayer is only five time; salat fajr, zuhr, asr, maghrib, and isha’. It is wrong normatively if there is someone do mandatory prayer less or more than five times.     

To perform prayer, all of Muslim agree that one of its requirements is to cover aurat. But, the question is whether each Muslim factually do the same way in covering aurat? 

The answer is no. It is because every single region has culture of clothing which is different. For example, Arabians wear robe to cover their body in the daily life. So when they are doing prayer, they are wearing robe. Americans and Europeans wear trousers and shirt. Then, when they are praying –for those who are Muslim , they wear trousers and shirt to over up aurat. Meanwhile, Indonesians wear sarong or trousers and batik when they are performing prayer for covering their aurat.

The way of how Indonesian Muslim attire for covering up their aurat in the prayer which is different with Arabian, Americans, and Europeans Muslim is one of small objects in the study of Islam Nusantara. Islam Nusantara has wide aspects such as history, social, politics, culture, fiqh, and so on.

So, Islam Nusantara is actually only concerned on the side of humanity (insaniyah) from Islamic teachings. For example, how Indonesian Muslim empirically practice Islamic teachings in accordance with their cultures by paying attention the provision of shari’a. In the side of humanity, Islam is different and not one because human is diverse. Islamic teachings is divine (ilahiyah) because it is the revelation from Allah. In this divine (ilahiyah) side, Islam is one.