Despite all of Muhammad's earlier warnings to his followers, immediately after his death, they became divided into sects and factions. More and more other sects and sub sects came into being as the Arabs conquered more and more different peoples with different outlooks and traditions fromAsia and Africa to Europe.
Sects such as the Khajerites, Shiites, Murje'ites, Mut'azelites, Asherites, Hanbalites and Sufis to name a few, predominated in certain parts of the empire at different times until they were overthrown by others.
The most fundamentalist and literalist sects were invariably formed by men of Arab descent while the most intellectual of early 'Islam' were not Arabs but men of Persian and Central Asian backgrounds, or Arabs who had been influenced by Greek, Hebrew and Persian ideas and had dropped their own primitive outllook.
The most unenlightened and traditonalist of all were those who believed in the literal words of the Quran and who closed their minds completely to reason such as:
Abu Mua'mmar al Hudhali (d. 236/850) who preached in Baghdad and who considered all those who did not agree that Allah has a corporial body like a human being is an infidel. Allah has ears, eyes, mouth, hands and feet just like any human.
Another similar believer was Ahmad b Hanbal (164/780-241/855) a famous lawyer and traditionist with adherents to his school. A later exponent of this school Ahmad b Tamiya was even more extreme that he condemned the Ghazzalis and Mut'azelites as heretics and unbelievers.
There were many more of these ignorant 'religious' bigots who made it impossible for Muhammadan Islam to progress intellectually and spiritually.
Even today, these degenerate ideas manifest themselves among theTaliban, Wahabis, Osama b Ladensand very many others.
'Ulamaa' such as these are the single most important cause for the eclipse of the so called 'Islamic Civilzation', because the latter only excelled under enlightened and liberal regimes.
6: 159 As for those who divide their religion and break up into sects[shiya'a]thou hast no part in them in the least: their affair is with Allah: He will in the end tell them the truth of all that they did.
19:37 But thesects [al ahzaboo] differ among themselves: and woe to the Unbelievers because of the (coming) Judgment of a momentous Day!
23: 53 But people have cut off their affair (of unity) between them into sects: each party[hizbi]rejoices in that which is with itself
30: 32 Those who split up their Religion and become (mere) Sects[shiya'a] each party rejoicing in that which is with itself!
Al-Tirmidhi HadithHadith 171Narrated byAbdullah ibn Amr
Allah's Messenger (peace be upon him) said: There will befall my Ummah exactly (all those) evils which befell the people of Isra'il, so much so that if there was one amongst them who openly committed fornication with his mother there will be among my Ummah one who will do that, and if the people of Isra'il were fragmented into seventy-two sects my Ummah will be fragmented into seventy-three sects. All of them will be in Hell Fire except one sect. They (the Companions) said: Allah's Messenger, which is that? Whereupon he said: It is one to which I and my companions belong Transmitted by Tirmidhi.
Sunan of Abu-DawoodHadith 4579Narrated byAbuHurayrah
The Prophet (peace be upon him) said: The Jews were split up into seventy-one or seventy-two sects; and the Christians were split up into seventy one or seventy-two sects; and my community will be split up into seventy-three sects.
Sahih Al-Bukhari HadithHadith 4.803Narrated byHudhaifa bin Al Yaman
The people used to ask Allah's Apostle about good, but I used to ask him about evil for fear that it might overtake me. Once I said, "O Allah's Apostle! We were in ignorance and in evil and Allah has bestowed upon us the present good; will there be any evil after this good?" He said, "Yes." I asked, "Will there be good after that evil?" He said, "Yes, but it would be tainted with Dakhan (i.e. Little evil)." I asked, "What will its Dakhan be?" He said, "There will be some people who will lead (people) according to principles other than my tradition. You will see their actions and disapprove of them." I said, "Will there be any evil after that good?" He said, "Yes, there will be some people who will invite others to the doors of Hell, and whoever accepts their invitation to it will be thrown in it (by them)." I said, "O Allah's Apostle! Describe those people to us." He said, "They will belong to us and speak our language." I asked, "What do you order me to do if such a thing should take place in my life?" He said, "Adhere to the group of Muslims and their Chief." I asked, "If there is neither a group (of Muslims) nor a chief (what shall I do)?" He said, "Keep away from all those different sects, even if you had to bite (i.e. eat) the root of a tree, till you meet Allah while you are still in that state."
*** Muhammad disallowed sectarianism amongst his followers and forewarned them of its dire consequences.
He repeatedly condemned the Christians and the Jews for their internal divisions; his followers turned out to be not at all different since that is exactly what they have done ***