Shia Islam is the second-largest denomination of Islam worldwide; it is also the state religion of Iran. Its followers are referred to as Shiites. Shia Islam is highly concentrated in the Middle East. Outside of Iran, Iraq, Lebanon, and Azerbaijan, Shia is a lopsided minority among Muslims. Even in nations with a relatively large Shia presence, such as Pakistan, India, and Turkey, the denomination is a small proportion of those who adhere to Islam. Overall, Shia is estimated at 10–15 percent of the global Muslim population.
More than 75 percent of the world’s Muslims are Sunni, the sect typically thought of as “orthodox” Islam. This makes it more effective to describe Shia Islam according to its differences with Sunni doctrine. Within Shia there are subdivisions, but nearly nine in ten Shiites are part of an approach known as Imamiyyah, or the “Twelvers.” This name comes from their belief in a dozen Allah-appointed spiritual leaders proceeding after Muhammad. According to most Shiites, the last of these imams has been hidden from the world for many centuries, a concept referred to as occultation.
The main schism between Shia and Sunni Islam is the proper succession of leaders from Muhammad. Sunnis believe the Islamic people should be led by a caliph, a role they bestow according to merit and consensus. By that measure, Muhammad’s son-in-law Ali was the fourth to hold leadership. Shiites, on the other hand, believe authority should be passed through the household of Muhammad. Accordingly, Shia Muslims believe the first proper authority over the Islamic people after Muhammad was Ali. The Arabic phrase Shiatu Ali means “the faction of Ali,” and the term Shi’a is a shorthand term meaning “followers.”
Whereas Sunni Islam defines Ali as the fourth caliph, Shiites consider him the first Imam. The term imam holds far greater significance in Shia Islam than it does to Sunnis. Imams, as defined by Shia Islam, are descendants of Muhammad endowed with a form of divine infallibility. The term is primarily applied to twelve specific men, although Shia Muslims may disagree on the identity of those twelve; in fact, this is the main source of sub-denominations within Shiism. Since there are only twelve true Imams in Shia Islam, their primary, day-to-day leadership comes from clerics. The most authoritative clerics are referred to using the title Ayatollah.
Shia Islam holds core doctrines identical to those of Sunni Islam concerning the Qur’an, the nature of Allah, and the role of Muhammad. Shia differs in a few notable points. These are underwritten by the choice of an entirely different set of hadith: the oral traditions used by Muslims to properly interpret the meaning of the Qur’an. The collection of traditions accepted by Shia Islam is almost entirely different from the traditions of the Sunnis.
In contrast to Sunnis, who pray five times each day, Shia requires only three prayers a day. Their formulation of the shahada—the Islamic declaration of faith—is slightly longer, since it includes an explicit reference to Ali. Their concept of Imams and Islamic succession also means that Shiites subscribe to a unique concept of the end times. Shia “Twelvers” also formulate the Five Pillars of Islam differently from Sunnis, and they add ten supplemental guidelines.
Compared to other Muslims, Shias more readily embrace two practices that are controversial even within the Islamic world. One of these is mut’ah, or temporary marriage. Under this concept, a man and woman can agree to briefly be considered “married,” allowing a social exemption for sex and other interactions, after which time they are no longer bound. The other concept is taqiyah, which is the permission to deliberately lie about one’s faith in order to avoid harassment. Technically, some type of taqiyah is allowed under all Islamic interpretations; however, it is given much greater latitude in Shiism, probably since Shias are often persecuted by Sunnis.
Shia Islam’s origins, its conflict with Sunni Islam, and its perspective on leadership are reflected in a greater degree of militancy. As compared to Sunni Islam, Shiism lends itself more easily to belligerent politics and heavy-handed government rule. Notorious quasi-political organizations such as Lebanon’s Hezbollah and the Iranian Revolutionary Guard are Shiite groups. In contrast, typical “pure terrorism” groups within Islam, such as Boko Haram, Al Qaeda, and ISIS, are part of a narrow subsect, Salafi, within Sunni Islam.