In Islam, a (فرض, farD; plural: فروض, furūD) is a mandatory duty, an obligation, for Muslims. As an example, the five pillars of Islam (testifying the faith, fasting, praying, paying religious taxes, and Hajj) are mandatory obligations on all Muslims.
There are two types of farD:
1. (فرض العين, farD al-‛ayn), meaning a farD that is mandatory on all Muslims. An example is praying: praying the five canonical prayers is a farD al-‛ayn on all Muslims.
2. (فرض الكفاية, farD al-kifāyah), meaning a farD that is mandatory on all Muslims of an area but whose requirements are fulfilled if enough people perform it; if enough people do not perform it, everyone will be guilty of a grave sin because of its non-fulfillment. An example is funeral prayers: whereas attending a Muslim’s funeral prayers (and other funeral needs) is mandatory on the Muslims of an area, if enough Muslims attend to the need then the requirement will be considered to be fulfilled for all. If not enough people attend to this obligation, everyone will be considered to be under sin for its non-fulfillment.
No one denies that jihad is a farD. (As there are three types of (جهاد في سبيل الله, jihād fi sabīlillāh, “struggling in the path of God”), for purposes of this post all references to “jihad” refers to (قتال في سبيل الله, qitāl fi sabīlillāh, “fighting or battling in the path of God”).) What is disputed among some jurisprudents is upon whom jihad is a farD al-‛ayn (and why) and upon whom jihad is a farD al-kifāyah (and why). This is important because it has important consequences on the choices and livlihood of Muslims.
Unlike issues that are always farD al-‛ayn (such as prayer), the issue of which type of farD jihad may be is taken on a region by region basis. The theory goes that in a region where Islam is supreme, jihad is a farD al-kifāyah. Jihad becomes a farD al-‛ayn upon the people of a region under the following conditions:
1. Infidels have invaded or are on their way to invade the region
2. The ruler has ordered his subjects to fight in defense of the region or for Islam
3. Hypocrites or impious Muslims (منافقين, munāfiqīn) are preventing Islam from remaining established in the region
4. Infidels or impious Muslims are threatening a nearby region that is unable to defend itself
5. To regain lands conquered by infidels or impious Muslims
When jihad becomes a farD al-‛ayn, it becomes compulsory on all who are able to fight to do so. If the ruler goes contrary to this, he must be disobeyed. If one’s parents order their child not to fight, they must be disobeyed. (When jihad is a farD al-kifāyah, one may be obligated to desist from jihad if ordered to do so by the ruler or one’s parents.)
The theory goes that jihad is a farD al-‛ayn when it must defend Islam, Islam’s hold on a region, or a region’s security; jihad as a farD al-kifāyah serves to protect Islam in the region, secure the region’s borders, and spread the realm of Islam.
But how does one determine when the requirements for jihad as a farD al-‛ayn have been met? Consider, for example, the often-made claim that infidel forces, in cooperation with treacherous Muslims, have invaded Afghanistan, Kashmir, Chechnya, and so on. Consider, also, the charge often levelled against supposedly Muslim governments that they are hypocrites, impious Muslims, in league with infidels and enemies of Islam. If their claims are correct, then it becomes a mandatory duty for all male Muslims in the relevant regions to do jihad against the infidels and impious Muslims. And then this mandatory duty spreads to regions near the relevant region under threat: neighboring people are also obligated to fight.
Some jurisprudents say that jihad cannot be fought without the Caliphate, or that jihad does not become a farD al-‛ayn without the Caliphate. To this promoters of jihad say that the presence or absence of the Caliphate does not and should not matter: what matters is the defense of Islam and its lands. Indeed, some say that the Caliphate cannot be reestablished without jihad waged to expel the infidels and punish corroborating Muslims.
In short: jihad is a mandatory duty, a farD al-‛ayn, on all Muslim men (in most of the world, anyway) until the infidels are defeated, treacherous Muslims repent or are punished, and Islamist regimes are instituted to rule the Muslims, with the ideal goal of reuniting Muslims under one Islamist Caliphate. This, of course, also concerns the reclamation of lands conquered by the infidels (Eastern Europe, Spain, and so on). Until these goals are met (or even more, as a previous post explained through a translation of an Urdu text listing the purposes and goals of jihad), jihad remains a farD al-‛ayn, and anyone who denies this is as if he denied the farD-ness of praying or fasting.
(Among various schools of thought there is disagreement as to the status of such Muslims who commit such a big sins: some hold them to be rebellious Muslims who must be made to repent, others hold them as rebellious Muslims who must be killed, and others hold them to have become infidels and apostates and must be killed.)