Can we say that non-Muslims such as Hindus and Buddhist are Kafirs? What is the true definition of the word Kafir?
Kafir in the terminology of the Quran (as affirmed by the late Allama Tabatabei in al-Mizan) is an expression for a disbeleiver who knowingly and arrogantly rejects Islam. Thus,“it’s equal to them whether you warn them or not they believe not” (Surat al-Baqarah, Ayah 6).
In the terminology of our jurisprudence it includes any non-Muslim including the enemies of Ahlul-bayt (known as Nawaseb who cursed Imam Ali and fought Ahlul-bayt).
Answered by: Sheikh Mansour Leghaei