Do religious scholars have the right to declare someone to be a Kafir (disbeliever)?
It is permissible to describe unspecified people as Kafir (disbelievers) based on their actions. Therefore, it is not wrong to describe any one who seeks help from people other than Allah for something which can only be sought from Him as Kafir. This includes beseeching a prophet or Waliy (pious person) to cure one's self or one's children.On the other hand, certain people may be declared as Kafir, when they deny a matter which is Ma`lum minad-din biddarurah (well-established religious matter); such as Salah (Prayer), Zakah (obligatory charity), or Sawm (Fast). In such cases, the person in question should be informed of the ruling and called to repent. If they do not repent, the ruler is obliged to execute them for their disbelief. If Takfir (declaring as Kafir) of certain persons for a religious reason had not been allowed, al-Had (prescribed penalty) of Riddah (apostasy) would have not be applicable.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.