4. Bangladesh 148.6 Million
Bangladesh is constitutionally a Secular Country. Although removed from the constitution once, it later came back again. Islam is the largest Religion of Bangladesh; Muslims constitute 90.4% of the population, followed by Hindus, who constitute 8.5%, and Buddhists, Christians, those who practice other religions and those who do not are the remainders. Religion has always been a strong part of identity, but this has varied at different times.
