shia
Shiites. refer to the related question listed below for more infomation.
Islam.
mostly Muslim and a small group are Christian
The dominant religion of Iran is Islam (majority Shi'ite), while the Baha'i Faith is the largest non-Muslim minority religion.
Most Iranians are Muslims; 92% belong to the Shi'a branch of Islam, the official state religion, and about 8% belong to the Sunni branch of Islam. The remaining 2% are non-Muslim religious minorities, including Bahá'ís, Mandeans, Yarsanis, Zoroastrians, Jews, and Christians.
ISLAM
Most Iranians are Muslims. Around 90%[1] belong to Shi'a branch of Islam, the official state religion, and about 9% belong to the Sunni branch of Islam. The remaining 0.4% are non-Muslim religious minorities, including Bahá'ís, Mandeans, Hindus, Yarsanis, Zoroastrians, Jews, and Christians
Most Iranians are Muslims; 92% belong to the Shi'a branch of Islam, the official state religion, and about 8% belong to the Sunni branch of Islam. The remaining 2% are non-Muslim religious minorities, including Bahá'ís, Mandeans, Yarsanis, Zoroastrians, Jews, and Christians.
Islam has had the greatest influence on the Constitutions of the Islamic Republic of Iran and Kingdom of Saudi Arabia.
Hinduism accounts for 80.5% of the population of India. Islam (13.4%), Christianity (2.3%) and Sikhism (1.9%). Islam and Christianity is growing rapidly in India.
Persia is the ancient name of Iran and Islam entered Iran near 1400 years ago. and when tragedy of karbala happened most of Iranians became shia.
I think that Iran has the most rate of IQ and its people have gorgeous cultural.