What is the fastest growing religion

The number of people celebrating Eid-al-Fitr this year, and in years to come, will grow as the world's Islamic population continues its growth. Source: Getty Images Europe

With the world’s population of Muslim people set to grow at twice the rate of the total population, fasting and other spiritual practices during the month of Ramadan are becoming more significant events around the globe.

But while Australia’s Muslim population continues its above-average growth since the 1970s, Islam is not the fastest growing religious group in Australia. Here's a closer look at the numbers.

Islam is said to be the fastest growing religion with the world's population of 1.6 billion Muslims predicted to expand to 2.3 billion by 2050, according to the

"By 2050, Muslims will be nearly as numerous as Christians, who are projected to remain the world’s largest religious group at 31.4 per cent of the global population," the report said. Muslims are predicted to make up 29.7 per cent of the global population by 2050.

Two population growth rates help explain this. The world's Muslim population is expected to grow at a rate of 73 per cent in the 40 years between 2010 and 2050; while the world's Christian population will grow at just 35 per cent during that period, which is roughly in line with the world's total growth rate.

Professor of Demography at Australian National University Peter McDonald said the accuracy of the Pew Research report would depend heavily on what assumptions were used, of which there would be many. Predicting a population of Muslims would be problematic, he said, since there were so many groups of Muslims.

Between 2010 and 2050 it's predicted Christianity will lose 60 million people to agnosticism and atheism, or other  "unaffiliated" ideologies. And while the absolute number of unaffiliated people will grow (particularly in western nations like US and parts of Europe), the overall proportion will drop.

The global "unaffiliated" population was estimated to be 1.13 billion in 2010 and is expected to grow to 1.23 billion by 2050. But the share of "unaffiliated" is predicted to drop from 16.4 per cent to 13.2 cent in this period, according to Pew Research.

The unaffiliated population was concentrated in places with low fertility and ageing populations, such as Europe, North America, China and Japan.

In contrast Hinduism, which is currently the world's fourth largest religious group, is projected to have flat growth at around 15 per cent between 2010 and 2050.

While an estimated 23.5 per cent of the world's population were Muslim in 2010, the last Australian Census revealed a different population make-up in Australia.

Just 2.2 per cent of Australians, or 476,300 people, identified as Muslim in the 2011 census. The actual number is likely to be larger as many people do not state their religion at the Census. estimated 2.4 per cent of Australians were Muslim in 2010.

But while the growth rate of Australia’s Muslim population has outpaced that of our total population, Islam is not the fastest growing religion in Australia. The figures show that Hinduism is the fastest growing religion here, which coincides with the growth in the number of Australians born in India.

"Four source countries dominate our [overall] intake: India, China, UK and New Zealand – more Hindus, Confucians and Christians entering Australia than Muslims by a very long way," Prof McDonald said.

Proportionally, the number of Muslim migrating to Australia is quite small. Yet perceptions about Australia’s Muslim population show a different picture.

A poll by 

research company Ipsos Mori

This could be because of the growing visibility of Islamic symbolism, said Mehmet Ozalp, Islamic Theologian at Charles Sturt University.

Islam was experiencing two kinds of growth: a quantitative growth of Islam's increasing population in Australia and around the world and a qualitative growth of Islam itself among Muslims who did not practice previously, he said.

“In Australia, 20-30 years ago, you would hardly see a woman covering her hair. There were Muslims then as well, in large numbers, but they weren’t really practicing that much," Prof Ozalp said.

The Pew Research report provides straightforward reasons: high fertility rates and the sizes of younger populations.

"Globally, Muslims have the highest fertility rate, an average of 3.1 children per woman – well above replacement level (2.1), the minimum typically needed to maintain a stable population," the report said.

"Another important determinant of growth is the current age distribution of each religious group – whether its adherents are predominantly young, with their prime childbearing years still ahead, or older and largely past their childbearing years."

Prof McDonald said birth rates would be the main driver of any population, with a few exceptions where migration is higher than normal.

One third of the global Muslim population is concentrated in Africa and the Middle East, areas which are predicted to have the largest population increases, and typically have very young populations.

“When you look at the age brackets in these societies, you will find that most of [those countries], 50 per cent [of people] will be under 25 years of age,” said Prof Ozalp.

“Same with Australia, the Australian Muslim community is very young, compared to the rest of the society. This shows that it’s largely driven by birth, rather than conversion.”

Prof McDonald said higher fertility was associated with lower GDP per capita, except at the top 10 wealthiest countries that have a higher fertility rate than the next 10 that follow.

So is there a relationship between a country's wealth and the faith most commonly practised there? Not necessarily, said Abdullah Saeed, Professor of Arab & Islamic Studies at the University of Melbourne.

"There are around 57 Muslim majority countries and most of these countries are still considered developing countries," said Prof Saeed. "Some of the wealthiest countries in the world are Muslim and equally many of the poorest countries are also Muslim."

Conversion, or "switching", is a factor in the forecast growth of the world's Muslim population, the Pew Research report said.

A "modest net gain" of 3.2 million people is forecast by 2050 as a result of conversion, but it does not account for the total population gain of 1.16 billion Muslims.

Prof Ozalp said conversions were a contributor to Muslim population growth, but not in the same magnitude as growth through fertility.