Islam

The scope of God's law, the shari'a, is as expansive and as comprehensive in Islam as is halakah in Judaism. In fact, all human actions and interactions fall into and are analyzed by Muslim jurists in one of five categories: (1) actions that God specifically commands (such as fasting and five daily performances of prayer); (2) actions that God encourages but does not insist upon (such as charity beyond what the zakat requires); (3) neutral actions about which God is indifferent; (4) discouraged but not prohibited actions (such as divorce); and finally (5) forbidden actions (such as murder and drinking alcohol). In very much the same manner as rabbinic law, Islamic jurists submit all actions to careful analysis in an effort to determine the will of God. Ultimately, submission to God lies in the considerable effort that devout believers invest in ensuring that all of their actions are measured in the light of and conform to the shari'a. This emphasis on the correctness of action among the faithful in both Judaism and Islam distinguishes these traditions as orthopractic and sets them both apart from Christianity, with its historic emphasis on orthodoxy, the correctness of doctrine, among believers.

Although Muslims, like Jews, historically focused primarily on faithful adherence to God's law, it is important to note that the shari'a is not in any sense a uniform legal code. Rather it is a legal framework within which considerable disputation occurs. Basing their analysis primarily on the Koran and extensive collections of reports, known as hadith, about what the Prophet did and said, as well as several subsidiary sources of divine law, Muslim jurists generated an immense body of jurisprudence over the centuries in their efforts to discern and apply the specific content of divine law.

Because Sunnis, unlike Shiites, never developed a clerical order or hierarchy, there was no body or institution in Sunni Islam charged with establishing definitively which legal opinions were authoritative and which were not. Again, very similar to the rabbinic system, jurisprudence in Sunni Islam is remarkably decentralized. The opinions of certain jurists gain authority over time as they are cited positively by subsequent jurists in their own legal opinions. Legal reasoning among Sunnis divided itself into a number of "schools" of jurisprudence known as madhahib in Arabic, of which four survive: Hanafi, Shaf'i, Hanbali, and Maliki. Although both the approach to legal reasoning and the specific content of law in each school do not vary greatly, there are some important differences among them. As a general rule these legal schools predominate regionally (for example, Malikis in North Africa and Hanbalis in northern and central Arabia). Shiites and Kharijites developed their own legal schools.

The decentralized character of authority in Sunni jurisprudence extends more broadly to the entire field of religious knowledge. Because there is neither a formal clergy nor any ordination process among Sunni religious scholars, referred to collectively in Arabic as the 'ulama' (Anglicized as ulema), the educational process through which individuals gained admission to the class of religious scholars traditionally tended to be highly personal. Again, much like the rabbinic system, promising students sought and were granted permission to study under recognized authorities. Upon the completion of their studies they received a certificate from the master certifying their competence in whatever field of religious science they had studied with him.

Like Judaism and Christianity before it, Islam was profoundly affected by its encounter with Hellenistic thought. By the early Abbasid period, speculative theology among Sunnis was dominated by a series of competing schools that emerged in response to various major doctrinal debates among the ulema over such issues as predestination versus free will, whether the Koran was created or coexistent with God, and the extent to which the Koran should be interpreted literally or metaphorically. The assistance of politically powerful patrons was frequently sought by partisans in these contentious debates among the ulema to ensure the persecution of their opponents.

Islamic mysticism, usually referred to as Sufism, like law, theology, and philosophy, also played a major role in shaping Sunni spirituality from an early date. In Sufism authority also tended to be both highly diffuse and personal in character. By the mid-thirteenth century an elaborate series of mystical brotherhoods, known as tariqas, emerged and replaced an earlier, more informal collection of individual mystics surrounded by their disciples. Under the tariqa system, with each brotherhood having its master and established rule of esoteric development, a greater measure of conformity to normative Sunni doctrine among mystics was finally achieved—to the great relief of mainstream Sunni ulema, who were frequently troubled by the more exuberant and ecstatic expressions of mystical gnosis among the Sufis.

The great mystical brotherhoods of the later Middle Ages also attracted large followings among all sectors of the population. Many people were especially attracted by the public veneration of great mystical saints, known in Arabic as awliya' (singular wali), "the friends of God," especially at the site of their tombs. In a religious system where prophetic revelation ended decisively with Muhammad's death in 632, wilaya, or sainthood, offered an important opportunity for mediation with God. Although many Sunni jurists opposed the cult of the saints, others found ways to accommodate this highly popular practice within the framework of normative Sunni practice.

Despite the fact that political and religious authority were theoretically unified for Sunnis in the office of caliph, as a practical matter, after the breakdown of centralized power in the Abbasid period, effective political power passed to and was monopolized by various regional dynasties and other secular political forces, which, nonetheless, frequently maintained the fiction that they were ruling in the name of the caliph. Philosophers, such as Abu Nasr al-Farabi (c. 878–c. 950), articulated elaborate theories of the caliphate and its qualifications long after caliphs ceased wielding effective political power. Thus the office of caliph continued to symbolize the ideal unity of the Muslim umma for Sunnis in a reality characterized by political fragmentation. Although the ulema class frequently decried the failure of secular political authorities to rule in accordance with the shari'a, the religious establishment came to see their primary role as guardians of the shari'a in a world without effective caliphs. Whenever possible they sought to pressure political authorities to adhere more closely to the shari'a, but the ulema effectively recognized a de facto division between political and religious authority from the Abbasid period onward.