According to the CIA World Factbook, around 90–95% of Iranian Muslims associate themselves with the Shia branch of Islam, the official state religion, and about 5–10% with the Sunni and Sufi branches of Islam.
According to the Islamic Republic's official survey, almost all of Iran's 82,000,000 people are Muslims, with 90 percent adhering to Shia Islam, and a majority of that Shia populace following the Twelver branch.
Until the 16th century, Persia was mostly Sunni. At the turn of that century, the Safavid dynasty conquered much of what is now Iran and made Shiism the official religion. The conversion was accompanied by a massive crackdown on Sunnis, so that over time much of the population became Shia.
About 90 percent of Iranians practice Shi'ism, the official religion of Iran. [i] By contrast, most Arab states in the Middle East are predominantly Sunni.
Twelver Shīʿas constitute the majority of the population in Iran (90%), Azerbaijan (85%), Bahrain (70%), Iraq (65%), and Lebanon (65% of Muslims).
Iran has 66 million to 70 million Shias, or 37-40% of the world's total Shia population.
In a poll conducted by Sabancı University in 2006, 98.3% of Turks revealed they were Muslim. Most Muslims in Turkey are Sunni Muslims forming about 90%, and Shia-Aleviler (Alevis, Ja'faris and Alawites) denominations in total form up to 10% of the Muslim population.
The Islamization of Iran was to yield deep transformations within the cultural, scientific, and political structure of Iran's society: The blossoming of Persian literature, philosophy, medicine and art became major elements of the newly forming Muslim civilization.
Not only Sunnis, but Shia Muslims who do not adhere to the official line of the Islamic Republic, are barred from entering the Iranian political sphere. In the case of Sunnis, the ban on political participation is explicit in Iranian law.
96.5% of Iranians Identified as Muslims. Survey conducted online on 50,000 Iranians and found 32% identified as Shia, 5% as Sunni and 3% as Shia Sufi Muslim (Irfan Garoh).
Morocco is home to 32,987,206 persons. Of the total population, 98.6% are Sunni Muslims while Shia Muslims compose less than . 1% of the population. Christians account for 1.1% and Jews .
Iran's Islamic revolution, which brought Shias to power in 1979, and the Sunni backlash have fueled a competition for regional dominance.
Islam in Lebanon has a long and continuous history. According to an estimate by the CIA, it is followed by 63% of the country's total population. Sunnis make up 31.9%, Twelver Shia make up 31.2%, next to smaller percentages of other Shia branches, such as Alawites and Ismailis.
Shia Islam in Afghanistan
Roughly 10% of the Afghan population is Shia. Majority of Shias in Afghanistan belong to the Twelver branch. This includes the Hazara ethnic group and the smaller urbanized Qizilbash group, who are originally from eastern Iran.
Shias comprise a majority in Iran, Iraq, Azerbaijan, and Bahrain, and a plurality in Lebanon, while Sunnis make up the majority of more than forty countries from Morocco to Indonesia.
Muslims comprise a number of sects: the majority practice Sunni Islam (estimated at 85–90%), while a minority practice Shia Islam (estimated at 10–15%). Most Pakistani Sunni Muslims belong to the Hanafi school of jurisprudence, which is represented by the Barelvi and Deobandi traditions.
The modern Kingdom of Saudi Arabia was formed in 1932 by the House of Saud, who are followers of a movement within Sunni Islam known as Wahhabism.
Islam is the main religion of the citizens of Kuwait and the majority of Kuwaiti citizens are Muslim; it is estimated that 70%–75% are Sunni and 25%–30% are Shias. In 2001, there were an estimated 525,000 Sunni Kuwaiti citizens and 300,000 Shia Kuwaiti citizens.
Religion of Saudi Arabia. Saudi Arabia is the birthplace of Islam, and most of its natives are adherents of the majority Sunni branch. In modern times, the Wahhābī interpretation of Sunni Islam has been especially influential, and Muslim scholars espousing that sect's views have been a major social and political force.
Gradually, an increasing number of laws were passed by the Rashidun Caliphate which regulated Zoroastrian behaviour and limited their ability to participate in society. Over time, the persecution of Zoroastrians by Muslims became increasingly common and widespread, and the religion consequently began to decline.
By 650 BCE, the Zoroastrian faith, a monotheistic religion founded on the ideas of the philosopher Zoroaster, had become the official religion of ancient Persia. Later Judaism and then Christianity came to Persia via Mesopotamia, with both developing vibrant faith communities in Persian lands.
The religion still survives to this day in small communities, mostly located in present Iran and India. The Zoroastrians in India are called Parsis.
According to the federal Ministry of Religious Affairs, more than 99 percent of the population is Sunni Muslim. Members of other religious groups combined constitute less than 1 percent of the population and include a small Christian community, a small Sufi Muslim community, and an unknown number of Shia Muslims.
Today's Afghanistan can be considered 99% Muslim. There is a rough 3/4 to 1/4 split in favor of Sunni Muslims to Shia. Though recent history has been defined by growing religious intolerance and sectarian conflict, Afghanistan does have marginal adherents of other religions.
The country with the single largest population of Muslims is Indonesia in Southeast Asia, which on its own hosts 13% of the world's Muslims.