Takfeer (Excommunication)
In Muslims, we witness that people belonging to a certain sect would consider in their hearts that the other person, of a different sect is not going to please Allah with any of his/her deeds. At extremes, even considering someone a non-believer, God forbid. We are all Muslims, and in no way can we put a stamp of a believer / non-believer as a result of the sect one belongs to.