My short response to a question by a sister in Hawaii on who a secular Muslim is.
My short answers are like this. There are different ways to define secular Muslims. First, they are those Muslims who believe in Islam, become part of Muslim community, but do not practice prayer regularly, do not go to Hajj and other ritual practices. People in the West define them as "non-practicing Muslims". Second, Muslims who believe and practice most rituals, but do not hold an integration between Islam and politics, nor integration between Islam and science; they believe that politics, science, and other worldly affairs are "profane" and should not be part the religious, or the Islamic. Third, a secular Muslim can be anyone who views himself or herself as a secular Muslim. This is more personal view of the meaning of "Islam" and "secularism" by the person.
For the question whether Indonesian Muslims were secular, the answer would depend on which definition we use. If we use the first definition, historically Indonesian Muslims were secular because they were many local Muslims who didnot practice prayer regularly or didnot prayer at all; they might celebrate religious festivals as "social events" rather than "religious ones". If we use the second definition, Indonesian Muslims in the past can be said secular when they separate religion from politics, such as Soekarno and Hatta. But on the other hand, Muslim kings integrated and combined the matters of religion and adat (custom) through the parewa sara and the parewa adat in Aceh kingdomes, Makassar, Gowa-Tallo, Banten and others. Still, on other hand, it can be said, Muslim kings and local people were actually "secular" in the sense that they retained local beliefs and practices such as spirit offerings, magic, bissue, etc, despite identifying "formally" with Islam. Today, Indonesians are mixed: mostly religious, some secular, but many are in grey areas, somewhere in between. We know that any attempt of categorization is a useful simplification of a complex reality.
I have intended to write about a book on the origins and development of Islamic secularism in Indonesia. So much more later.