Kafir – One who hides or denies the truth. In the religious context, a kafir is the one who denies the existence of Allah and the prophethood of Mohammad (SAW) as the last and final prophet.
Generally speaking, there are two types of Kafirs:
• Zimmi - one living within the jurisdiction of an Islamic government and enjoying the security and legal protection.
• Herbi – one who is in the state of war with Islam.
It is notable to mention that not every non-Muslim is a kafir. Jewish, Christians and Sabeans are referred to as the “People of the Book” and they are not Kafirs.
Idol-Worshippers (Mushrik) fall in the category of Kafir because they associate other gods, a person, thing or a natural object like the Sun, Moon or a star with Allah.
In the context of Kafir, it is appropriate to quote the Quranic verse 9:5, which addressed the Muslims of the time of the exalted prophet, “to kill the kafir wherever you find him...."). This verse specifically refers to the groups of people of Mecca who had already committed crimes against the Holy Prophet and his companions by.
• Spreading thorns in the way and throwing stones at the Holy Prophet and his companions,
• Carrying out social boycott of the Holy Prophet and his companions
• Provoking the people of Taif to throw rocks at the Prophet,
• Planning to kill the prophet while he slept at night, and
• Looting the homes of the Holy Prophet and his companions when they left Mecca for Medina.
Although, Quran (9:5) directed to kill those Kafirs, some were forgiven by the Holy Prophet because they repented and accepted Islam.