Mohammed was succeeded as ruler of the new Moslem empire by a relative, Abu Bakr, who took the title of Caliph, or successor. During his two year caliphate (632-634), he collected the teachings of the prophet and issued them as the Qur'an or Koran. Abu Bakr made the Qur'an (Koran) the basis for all governance and laws. The strict unification of political and religious governance and life became a central tenet of early Islam. One ruler in both spheres: one law in both spheres. Islam spelled out exact rules for life. These rules represented a civil and religious code. There was no concept of a separation of church and state under early Islam.
In addition to the Caliphate and the Qur'an, the ulema or ulama also emerged as an important institution during the reigns of the first four Caliphs. Taking its origins from the Prophet at Medina, the original ulama represented the "Companions" of the Prophet and then the companions of his early successors. As time went on, of course, they ceased to be companions and became wise, religious advisors to the caliphs and, with time, judges to enforce the Qur'an. The ulama comprised people who were learned in the teaching of the Qur'an and pious. Be careful in reading the textbook [Craig...] on this institution. They were originally simply an advisory body working with the caliph to centrally control morals and religious practices. However, by the ninth century, there came to be several ulama. By this time they had become almost regional courts, enforcing proper Moslem practice.
The Ommayad or Umayyad caliphs (a Meccan family) took command from 634 to 754, beginning with Omar (634-644), who was the second Caliph. Uthman followed as the third Caliph (644-656). Ali, a cousin and son-in-law of Mohammed, followed as fourth caliph. But his caliphate was contested by Mu'awiya. The result was a civil war from 656-661, which ended when Ali was assassinated (661) by a disaffected, radical Kharijite. The Kharijites, a radical group, were motivated by their belief that Ali had compromised the principles of the Prophet and Qur'an. They believed that the Umma, or Moslem community of the faithful, must rigorously and strictly follow the Qur'an. The Kharijites insisted that true Moslems, including the Caliph, must follow the Qur'an literally. The caliph must be a moral example. The individual and the Umma as a whole must be true to the faith. They also taught that all Moslems were equal, which meant they were all responsible for themselves individually and for the Umma collectively. Hence, the Kharijites were a source of rebellion throughout the Ummayad reign, but they have remained a major force, in a milder form, ever since, especially in West and North Africa.
The assassination of Ali in 661, ironically, provided the basis for the rise of another radical movement within the Moslem community; that of Shi'ism. The Shi'a (from Shi'at Ali) held that Ali and his descendents were the only true caliphs because, according them, Ali was the true imam; that is, the one appointed to succeed by the Prophet himself. [Shiites hold that Ali was not only a blood descendent, but the appointee of Mohammed.]
These Shi'ites, rallied around Ali's son, Husayn, who was the focus of resistance to the Ummayad in Iraq. But, in 680, the Ummayad then defeated and killed Husayn. The death of Husayn forced the Shi'ites underground. In the early period, what held the Shi'ites together was mostly loyalty to the bloodline of Ali (and his mother Fatima, daughter of the Prophet). As time went on, Shi'ism developed a full ideology, not too dissimilar from that of the Kharijites.
After Ali's death (in 661), then, Mu'awiya became the fifth caliph and his descendents ruled as Ommayads until about 754. The Ommayad caliphs moved the capital of their empire to Damascus in Syria: even though the unification of political and religious matters continued, this was a significant change because Mecca continued to be the religious center while Damascus was not religiously significant. The Ommayads extended their power over much of what had been the ancient Roman and Persian empires. The zenith of centralized Arab power over the Moslem world came under these rulers. Their empire ultimately stretched across the dry-belt arc.
In the year 744, the Abbasids (Abbas clan claimed descent from Abbas, an uncle of Mohammed) rose in rebellion and claimed the caliphate. Hence, the provoked a major civil war from 750-754, of which they were the winners. The Abbasids then reigned from 754 until the mid tenth century, when their empire gradually fell apart. They continued the expansion of the empire, where they could. The civil war around 750-754, however, resulted in the division of the empire into two parts. An Ommayad descendent escaped to the far West with the help of other dissidents and established the so-called Spanish Ommayad state and dynasty. This Spanish Ommayad state controlled Iberia and northwestern Africa and it lasted from 756 to about 1030. At one point, in 929, this dynasty became powerful enough to claim the universal caliphate.
The Abbasids also caused further religious division and struggle among Moslems. In 762, the Abbasids moved the capital to Baghdad (in present-day Iraq), symbolizing how these rulers toned down the spirituality of the empire and became more worldly. Some of you may prefer to say that this move symbolized the decline of spirituality. More significant, the Abbasids ended the unification of religious and political competencies. While they continued to hold political power, the Abbasids turned religious authority over to the ulama, those "persons of right knowledge." Jurisdiction in religious and moral matters became the responsibility of local boards comprised of educated men who were experts in the Qur'an and Tradition of Islam. One should emphasize that the ulama became strictly local boards. In every good-sized town, there was a local ulama that sat to hear cases of breach of the Moslem law and to rule over the local faithful in religious and moral matters. The ulama also comprised the teachers of the sacred law, on the local level. So let us note carefully, not only were religious and political competencies separated, but centralized control of the religion and morals was abandoned. The ulama had control of peoples' everyday lives except as they owed allegiance on the tributary basis with the empire at large. Hence, the Moslem world returned to the age-old imperial monarchy system. The Shi'ite ideology crystallized in response to this secularization.