The Pew Foundation has recently released a major worldwide survey of religion. As can be seen from the basic breakdown, Christianity is the largest in number of adherents, with Islam in second place. Here is the discussion of Islam:

Muslims number 1.6 billion, representing 23% of all people worldwide. There are two major branches of Islam – Sunni and Shia. The overwhelming majority (87-90%) of Muslims are Sunnis; about 10-13% are Shia Muslims.8

Muslims are concentrated in the Asia-Pacific region, where six-in-ten (62%) of all Muslims reside. Many Muslims also live in the Middle East and North Africa (20%) and sub-Saharan Africa (16%). The remainder of the world’s Muslim population is in Europe (3%), North America (less than 1%) and Latin America and the Caribbean (also less than 1%).

Although a majority of the world’s Muslims live in Asia and the Pacific, only about one-in-four people (24%) in that region are Muslims. By contrast, the Middle East-North Africa region has an overwhelmingly Muslim population (93%), but they represent only about 20% of the world’s Muslims. Muslims also make up about three-in-ten people in sub-Saharan Africa, 6% of those who live in Europe, 1% of North Americans, and less than 1% of the population of Latin America and the Caribbean.

The 10 countries with the largest number of Muslims are home to fully two-thirds (66%) of all Muslims. The largest share lives in Indonesia (13%), followed by India (11%), Pakistan (11%), Bangladesh (8%), Nigeria (5%), Egypt (5%), Iran (5%), Turkey (5%), Algeria (2%) and Morocco (2%).9

Muslims make up a majority of the population in 49 countries. Nearly three-quarters of all Muslims (73%) live in these countries. Although Muslims are a minority in India (14% of the total population), India nonetheless has one of the largest Muslim populations in the world (in raw numbers).

To read all the details on Muslims, check out the Pew website.