Takfir

Takfir is a term used by some Muslims to describe how they view a person who is not Muslim. They believe that such a person has done something that is against their religion and is considered an "unbeliever." This belief can be very serious because it means that Muslims may not be able to be friends with people who are not Muslim. If a Muslim believes someone is an unbeliever, it could mean that person is not allowed to be part of their community. So in other words, it's a way for some Muslims to separate themselves from those who don't follow their religion.