The accolade "Fastest Growing Religion" is sought by many groups. It is most commonly and vociferously claimed by Islam.

Statistics on religious adherence are difficult to gather and often contradictory; statistics for the change of religious adherence are even more so, requiring multiple surveys separated by many years using the same data gathering rules.

Religions can grow in numbers due to Conversion or due to population growth (assuming that children take on the religion of their parents).

Growth can also be in terms of absolute numbers or in terms of percentage growth per year. In terms of absolute numbers the larger religions will dominate, in terms of percentage the smaller ones. For example if a religion had only 10 followers a single addition would be a 10% increase, and would therefore dwarf growth rates of the larger religions.

Claims for Fastest Growing Religion

In terms of percentage change the fastest growing religion in the USA is Wicca (2001 Aris Study) It went from 8,000 in 1990 to 134,000 in 2001. Their numbers of adherents are doubling about every 30 months[1]. It is also claimed as the fastest growing religion in Scotland[2], Australia and Canada.

In 1997 futurist John Gary stated that Islam is the fastest-growing of the major world religions. This is driven by the higher birth rates in the third world. [3]

Scientology also claims to be the world's fastest growing religion [4]