In how many countries is Islam the main religion?
There are about 50 countries in the world where the majority of the population is Muslim.
Among them are about 30 countries with a majority Muslim population, where more than 90% of the inhabitants belong to Islam (see list below). There are another 20 countries with a Muslim population of between 50% and 80%.
In 26 countries, Islam is the state religion by constitution. (see list below)