Islam is the largest religion of Bangladesh, the Muslim population is over 130 million (the Fourth-largest Muslim population in the world after Indonesia, India and Pakistan), and constitute nearly 88% of the total population, based on the 2001 Census. Religion has always been a strong part of identity, but this has varied at different times. A survey in late 2003 confirmed that religion is the first choice by a citizen for self-identification; atheism is extremely rare. Islam is the official religion of The People's Republic, as stated in the Constitution of Article 2A (inserted by the Constitution Eighth Amendment Act, 1988). The United Nations has recognised the country as mainly moderate Muslim democratic country

Hinduism is the second largest religious affiliation in Bangladesh, covering more than 13% of the population, according to the Bangladesh Bureau of Statistics. In terms of population, Bangladesh is the third largest Hindu state in the world after India and Nepal.
In nature, Bangladeshi Hinduism closely resembles the forms and customs of Hinduism practised in the neighbouring Indian state of West Bengal, with which Bangladesh (at one time known as East Bengal) was united until the partition of India in 1947.

Buddhism is the third largest religion in Bangladesh with about 0.7% of population adhering to Theravada Buddhism. Most of the practitioners are from the south-eastern district of Chittagong and Chittagong Hill Tracts.

Most of the followers of Buddhism in Bangladesh live in the south-eastern region, especially in the Chittagong and Comilla district. The leader was said to be Engr. Tarun Barua(Tipu), Rangamati, a promising, understanding,caring human being. There are also people of Arakanese descent living in the subtropical Chittagong Hill Tracts. Most of these people belong to the Chakma, Chak, Marma, Tenchungya and the Khyang, who since time immemorial have practiced Buddhism. Other tribals, notably those who practice Animism, have come under some Buddhist influence, and this is true in the case of the Khumi and the Mru, and to a lesser extent on the other tribes.

Christianity arrived in what is now Bangladesh during the late sixteenth to early seventeenth century AD, through the Portuguese traders and missionaries. Christians account for approximately 0.3% of the total population.