Kafir (Infidel)

Theologically implicating one to hell, the word "kafir" is highly charged and accusatory, no matter its use, but finds slight nuance in meaning depending on who it is used to describe as well as who is using it as a descriptor.

The word is also contrasted with the "jahiliyyah" or "ignorance" that is said to have existed prior to the advent of Islam. In this respect, contrasted with the period of ignorance, those around subsequent to the revelation of Islam cannot be considered to live in an age where Islam is unknown, hence making a justification of unbelief impossible.

It should be noted, however, that even while the pre-Islamic Arabs were admittedly "jahil" or "ignorant", they are still considered kuffar - even Muhammad's father, Abdullah, and mother, Aminah, were described by Muhammad (as recorded in Sahih Muslim) as "burning in Hell". Ignorance, thus, it would appear does not absolve one of their kufr (that is, the act of disbelieving or being a kafir).

Many Sunni theologians found the narration on the fate of Abdullah and Aminah troubling and ultimately decided to ignore the narration, overriding it on theological and moral principle. Indeed this was so troubling to the early Muslims that hadith were fabricated arguing that Abdullah and Aminah had been resurrected subsequent to Muhammad's declaration that they were burning in hell, in order to convert to Islam, die once more, and enter paradise. This hadith was later acknowledged, however, to be a fabrication. While theologians continue to have a hard time consigning the ignorant to hell under the label of "kuffar", Islamic scriptures are more clear.

In the case of non-Muslims

The root of the word "kafir" means "to conceal", and thus the word "kafir" literally means "one who conceals" and entails insincerity and even active deception on the part of the person being labeled a "kafir". That orthodox Islamic doctrine (following upon the Qur'an) categorically describes non-Muslims as kuffar can prove problematic in an an interfaith context, as it suggests that all non-Muslims are deliberately deceiving themselves and others by not embracing Islam which they, in fact, know to be true.

The other meaning implied in the root of the word "kafir" is "to be ungrateful", thus allowing the word "kafir" to be alternatively translated as "ingrate". This is likewise problematic in interfaith contexts as it entails the suggestion that all non-Muslims are somehow or the other ungrateful beings, in special distinction from Muslims, who are not so ungrateful.

In the case of Muslims

The word is also often used in the Qur'an as descriptive of Muslims who commit grave sins which offend Allah, though this meaning is more broadly understood to be metaphorical, as Sunni and Shi'ism theologians did not consider sins (other than polytheism) as causing one to constitute the act of apostasy, as this would have severe legal implications.

In this metaphorical sense, the word kafir can be understood to mean "ingrate", and is commonly used alongside and interchanged with such similarly insulting and accusative titles as faasiq, meaning "sinner" or "corrupted person", and munafiq, or "hypocrite". As a result, the word "kafir" finds frequent use in the Muslim world as an extreme form of insult or rebuke.

Kharijite, literalist interpretations

One of the first heretical sects in Islamic history were the Kharijites who defected from the party of Ali (shi'at Ali - these were the proto-Shi'ites) during the first civil war (fitnah) of Caliphal succession. This group distinguished themselves from other Muslims by their literal interpretation of scriptures which describe sinful Muslims as non-believers. On this interpretation, any Muslim who committed a sin or, in their assessment, failed to judge "by what Allah has revealed" (that is, in this particular case, those who did not follow Islamic political injunctions) was a disbeliever and, consequently, an apostate deserving nothing short of war and death.

This approach ultimately devolves to the practice of declaring that someone who describes themselves as Muslim is, in fact, a non-Muslim or, worse, and apostate. This is known as takfeer, or excommunication. Many extremist and jihadi salafist Muslims today employ this practice to justify their attacks on other Muslim populations who disagree with, in practice or word, their interpretation of Islam.

Although Christians and Jews are called the People of the Book (أهل الكتاب ahl al-kitab, a special title given by the Qur'an), orthodox Islamic teachings qualify them as disbelievers^[3][4][5], and hence kuffar.

Qur'an

Acts described in the Qur'an as constituting kufr, or unbelief.

Calling on anyone other than Allah (i.e. for intercession).

Disliking Allah.

Sacrificing to anyone other than Allah.

Disliking Islam or anything Islamic.

Joking about Islam or anything Islamic.

Disbelieving in any of the Messengers.

Judging by any other law aside from Islamic law.

Forbidding what Allah has made lawful, or make lawful what Allah has forbidden.

Believing in any other religion.

Leaving Islam.

Giving assistance to disbelievers against Muslims.

Disbelieving in Muhammad.

Guidelines on how to deal with disbelievers

The Muslims must remain united in opposition to the disbelievers, and maintain faith, while refusing to take the disbelievers as friends. If the disbelievers acquiesce but then return "to enmity", they must be slayed, unless they have a treaty with the Muslims or seek refuge amongst them. Finally, if the disbelievers "incline to peace", so too should the Muslims.

The "sword verse", or ayat as-sayf, in Arabic. The subsequent verse appears to present a conditional reprieve: