Bengal has two main religions, Hinduism and Islam, but within both faiths there is a great deal of diversity of culture, belief and practices.
Islam was brought to Bengal in the eleventh century, when Mughal empire builders from north India and central Asia sought to control the region. The early Muslims of Bengal were mainly people used to living in towns – most were soldiers, but there were also traders, craftsmen and religious leaders. They came from all over South and Central Asia and the Middle East. Islam only began to spread quickly among the local peasant and farming population from the sixteenth century onwards, when the Mughal emperor Akbar encouraged 'soldier-saints' to clear the thick forest areas to the east of the delta and use them for farming. Many of these 'pirs' or 'soldier-saints' and their converts followed forms of Islam that were only found in Bengal.
By the twentieth century, Muslims had become a majority of Bengal's population, and were a third of all South Asians. However, there was a big difference between the ashraf (elite and aristocratic Muslims, who usually spoke Persian) and the common folk or atrap Muslims, who spoke Bengali and were mainly peasants. Bengali Muslims belong overwhelmingly to the Sunni division of Islam, although there are small Shia communities, found mainly in Dhaka in Bangladesh and Murshidabad in West Bengal.
Bengali Muslims celebrate the major festivals of Islam: the Id ul-Fitr, which marks the end of the Muslim month of fasting (Ramadan) and the Id ul-Adha, or 'feast of the sacrifice', which takes place after the annual pilgrimage (hajj) to Mecca. Id ul-Adha is in honour of the story of the prophet Ibrahim's willingness to sacrifice his son at God's command. Even though Bengali Muslims are Sunnis, they also observe the festival of Muharram, usually associated more with the Shia division of Islam. This festival is held to remember the death of Hussain, grandson of the Prophet Mohammed and martyr of the faith.
Hindus are also divided, mainly by caste (social division), and Hinduism in Bengal also takes many forms. Shaivite Hinduism in the region is known for the strength of its Mother Goddess cults, 'Durga Puja' and 'Kali Puja'. These are among the main annual festivals and are widespread among the upper castes. Vaishnavite Hinduism, on the other hand, involving devotion to Krishna, is popular among the lower castes. Especially important is the annual festival of the Lord Shiva (gajan). The goddesses Lakshmi (of wealth and good fortune) and Saraswati (of learning and culture) also have annual ceremonies.
In addition to formal worship at Hindu temples and Muslim mosques, popular worship involving religious folk music is widespread, especially at Vaishnavite gatherings where kirtans (or collective singing of devotional songs) are popular both in the towns and villages. There are many Muslim followers of several Sufi orders. Bengali Muslims are also known for their practice of 'pirism', following Muslim saints or holy men (called 'pirs'). Popular religion in Bengal often mixes both Hindu and Muslim folk beliefs and practices. Bengal is famous for its wandering religious folk musicians (Bauls) who refuse to accept traditional differences between Hinduism and Islam in their worship and way of life.
Important folk deities worshipped by Hindus and Muslims alike include the 'goddesses of the calamities': Sitala, goddess of smallpox; Olabibi, goddess of cholera; Manasa, goddess of snakes; Bonbibi and Gazi pir, who protect against man-eating tigers; and Dariya-pir who controls the currents and crocodiles of Bengal's mighty rivers – and all have their annual festivals and devoted followers.
For members of all religious faiths, the annual New Year celebrated on the first day of the Bengali month of Baisakh, on 14 April, marks the beginning of spring and is a joyous occasion celebrated by all.
The majority of Bengalis in Britain are Muslim, with over 92% identifying themselves as Muslim in the 2001 Census (around 260,000 people). Bangladeshi Muslims account for nearly 17% of Britain's Muslim population, the second largest group after Pakistanis. In addition, 0.6% of Bangladeshis in the UK are Hindu, 0.5% Christian and 0.1 % Buddhist. In the Census, 5.8% did not state their religion and 0.4% said they did not follow any religion at all. Traditionally, Bangladeshi Muslims are Sunnis, allied to the Barelvi tradition, which emphasised the role of customs, shrines and pirs (saints) and was mixed with Hindu traditions and customs. From the 1980s onwards, however, the community has witnessed a process of Islamicisation which draws on alternative traditions stressing a 'purer' version of Islam. This shift has been of particular importance among younger British-born Bangladeshis.
Since the 1980s, there has been a growth of religious organisations within Bangladeshi communities, many with roots and funding from Muslim majority countries in the Middle East and Pakistan, as well as Bangladesh. Groups such as the YMO (Young Muslim Organisation) and the IFE (Islamic Forum of Europe) have focused on work with young people, and there has been the development of a strong Islamic identity amongst sections of the younger generation of British Bengalis.