The Guardian’s John Pitcher offers some expat insight on Indonesian religious tolerance:
Where a church is used for the initial wedding ceremony Muslim family members sit with Christians or, if they feel uncomfortable, they sit outside near the door and join in that way; all, regardless of formal religious faith are Javanese and what binds them is something much more powerful than any monotheist belief. It is what brings us all together for Selamatans (ceremonies), especially those for births and for the marking of the stages of different aspects of the life of a child, the mystic protection of an adult, or the building of a house. When the person leading the prayer section of a selamatan is a Christian the Muslims sit quietly and respectfully as the prayers are said. The other way round and the Christians do the same.