I have to disagree on that, it is beyond religion now. Whether Christianity or being a Muslim, it has nothing to do with ISIS for which Christians and Muslims before the Maute attack happened, are living harmoniously, yeah there are a little fire at some point because of religion conflicts but they sure get together well. That's why Marawi City became a good city. Now the incident had tarnished the relationship between Christians and Muslims in Marawi, and even those Muslims are victim of the bad Muslim's doings. The purpose of ISIS is somewhat related to their religion but they don't demand to Christians to convert to Islamic, but they are asking whether you are a Muslim or not, if not then you will die instantly by their guns.
Here you go again. Even before the Marawi clashes, the relations between Muslims and Christians were not good in Mindanao. The Moro Islamic Liberation Front waged a violent rebellion for many decades, before laying down their arms.