Who do Muslims consider to be an infidel and how should they treat them?

The term "infidel" originates in the 15th century from the Latin "infidelis" or the French "infidele" from in, meaning "not," and fidelis meaning "faithful." Today, according to the American Heritage Dictionary, an "infidel" is "one with no religious beliefs; "one who is an unbeliever with respect to some religions, especially Christianity or Islam;" or "of, or relating to unbelievers."

While some people have translated or conflated the word "infidel" with the Arabic term kafir, it is not synonymous with the Arabic although some aspects are similar. The term kafir was originally defined as a person who rejects God or who hides, denies, or covers the truth. In the Qur'an, the term kafir is generally used to describe a person who not only rejects belief in Islam but also takes an antagonistic stance towards Islam and Muslims; the discourse is generally in the context of the Meccans who opposed and fought against the early Muslims.

In most English translations of the Qur'an, the term kafir is generally translated as disbeliever, not infidel. In modern use, the word kafir is often used merely to mean a non-Muslim.