In Islam, your humanity is dependent upon your belief in and practice of Islam. This is why Muslims murder non-Muslims, because according to Islam, if you are not a believer, you are not human and can be murdered on a whim. At the same time, if you are a Muslim and somebody disagrees with how you practice Islam or thinks you are not “Islamic” enough, he can also call you not just less of a human being, but also an “apostate.” This is why Muslims are even more violent to each other than non-Muslims, such as in this one case where ISIS terrorists said that fifteen Muslims were not “Islamic” enough and so beheaded them in public:
Islamic State (ISIS) extremists executed 15 civilians on Thursday in Syria’s eastern Deir ez-Zor Governorate. A sharia court, run by the Islamic State (ISIS), charged them with violating religious law and thereby renouncing Islam.
“The Sharia Court charged the victims with apostasy and ordered ISIS executioners to behead them in public,” local media activist Dahham al-Ali told ARA News.
The 15 civilians were beheaded in front of hundreds of people in the Sabhiya District of Deir ez-Zor.
“It was a horrible thing to see. People were terrified and everyone remained silent while these brutal executions were taking place,” an eyewitness told ARA News, speaking on condition of anonymity.
“The group hasn’t even explained what those people have done to deserve this. ISIS just accused them of being apostates and beheaded them,” another witness said. (source)