After having bgeen subjected to all the media hype about ISIS (or ISIL, or IS... all meaning Islamic State), I thought I should read up on this subject of Islam.
Then, on another website, I found: "There are two main branches of Islam: Sunni and Shi'a. Sunni Islam is by far the largest group, although in some countries it is a minority."
Sunnis have their historical roots in the majority group who followed Abu Bakr, an effective leader, as the successor of Muhammad, instead of his cousin and son-in-law Ali.
Shi'ites are those who followed Ali, the closest relative of Muhammad, as Muhammad's successor.
source: Compare Shia vs. Sunni Islam
The difference between Sunni and Shia sects
The difference between Sunnis and Shi’a is more of a political nature than creed. There are no dogmatic differences between the two sects. Both, Sunnis and Shi’as, believe in the one God (Allah in Arabic) or Tawhid (monotheism), in the angels, scriptures, prophets and messengers, the hereafter, and the divine decree, destiny. They share the same scripture, called the Qur’an. Although there may be a difference in the way Sunnis and Shi’as worship, nevertheless, both pray five times a day, fast the month of Ramadan, pay the zakah (or the obligatory charity) and go to Mecca for pilgrimage. During daily prayers, both Sunnis and Shi’as direct their faces toward Mecca.
After the death of Muhammad, Muslims disputed over the prophet’s successor. Muhammad’s successor, Abu Bakr, and the other three Caliphs (Omar, Uthman and Ali) after him were accepted by Muslims as the rightful successors of the prophet and were later known as Sunnis. On the other hand the Muslims who thought Ali Bin Abi Talib, the prophet’s cousin, is the legitimate successor of the prophet became to be known as Shi’a. The Shi’a believes that the prophet’s successor has to be from the family of the prophet Muhammad. Whereas Sunnis believe that the successor of the prophet must be from the tribe of Quraish, the prophet’s tribe. This political discord continued for centuries and the divide between the two sects remains to this day unresolved. Another major difference between Sunni and Shi’a is that Sunnis believe that no person after Muhammad is infallible while the Shi’a believes in the infallibility of the twelve Imams (leaders) who are descendants from the family of prophet Muhammad.
The word “Shi’a” in Arabic literally means a sect or a faction. The followers of the Shi’a sect belong to the faction or followers of Muhammad’s cousin and son-in-law, Ali who, according to the Shi’a sect should have been the direct successor of Muhammad and is considered divinely appointed and the first Imam.
source: Difference between Sunnis and Shi’a
More on differences between Sunni and Shia sects
One (and one only) statement in what I read made some sense to me. Here is that statement: In Islam, God is beyond all comprehension and Muslims are not expected to visualize God.
After reading all the nonsense and after exploring the related links listed above, I found nothing at all to change any of my previous thoughts and judgments -- I still believe that all organized religions are, quite obviously, ludicrous crocks of human offal.