During the time of the Prophet and the time of the first three leaders
(or Caliphs) after his death, the Muslims were one single community,
even though there were some disagreements in governance particularly
during the term of the third leader (Uthman ibn Affan, 644-656 CE).
Political dissent and ultimately rebellion emerged during the term of the
forth leader (Ali ibn Abi Talib, 656-661 CE). The ensuing conflict and
war resulted into three factions; those who were fighting Ali, those who
agreed with the arbitration between Ali and his opponents, and those
who were initially with Ali but disagreed with the arbitration with the
opponents of Ali. So historically, the divisions in the Muslim community
were political in nature. At this juncture in the Islamic history political
authority began to be separated from the legal authority; many Muslim
scholars arose in the three camps who gave shape to the principles and
concepts of determining Shari’ah which were already being used. Great
Muslim jurists appeared like: Jabir bin Zayd (639–709 CE), Abu Hanifa
(699–767 CE), Ja’afar Sadiq (702-765 CE), Malik (711–795 CE), Shafi’i
(767–820 CE), and Ibn Hanbal (780–855 CE). Each of these scholars
referred to as Imam, an honorific title for outstanding religious and legal
scholarship, developed a methodology of deducing laws and legal rulings
and gathered a circle of followers. By the 10th. Century, the principles laid
down by these great scholars had developed into well-defined “Schools
of Jurisprudence” which adopted the exclusive allegiance of the scholars.
Thus, the school of Jabir bin Zayd became known as Ibadhi, that of Abu
Hanifa became known as Hanafi, that of Ja’afar Sadiq became known
as Shia’, that of Malik became known as Maliki, that of Shafi’i became
known as Shafi’i, and that of Ibn Hanbal became known as Hanbali,
though none of these Imams intended to create any distinct school.
Over the next three centuries, ordinary Muslims also came to adhere to
a particular school and owe exclusive allegiance to it for any legal and
religious rulings in response to issues of concerns.

With all these “Schools of Jurisprudence”, Muslims are all united by one
common scripture, the Qur’an, which has remained unchanged since its
revelation over fourteen centuries ago, and the traditions of the Prophet
Muhammad, peace and blessings of Allah be upon him. Muslims all over
the world do not differ in the principles of faith and religion and perform
religious rituals such as prayers and pilgrimage in unity.

It must be noted that Islam forbids division of religion into sects. Allah
says in the Qur’an 3:103,

"And hold fast, all together, by the rope which Allah (stretches
out for you), and be not divided among yourselves."

In the spirit of this command, all Muslim schools of Jurisprudence lived
as one single community in harmony for centuries. The unfortunate
Muslim conflicts which we have seen in history and which have erupted
in recent times have nothing to do with the religion, but they are about
the geo-political struggles.