John H Williams

(Investigator 114, 2007 May)

In Investigator 112 Bernhard Stett provided an article on the religious Top Ten of Everything in 1989 and 2005.

The World Christian Encyclopaedia (D B Barrett, 2001) is the "world standard". It gives the world total 'non-religious' at 948 million (12.7%) plus 150 million atheists (2.5%).

What struck me was the apparently dramatic growth in atheism (152 million in 2005 The Top Ten Of Everything) and agnosticism (772 million).

Neither figured in the 1989 list: these two 'non-religious beliefs' were not regarded as religions in the 1989 edition, but were in 2005. The total 'non-believers' at 924 million is below Barrett's 948 million and is about four years 'younger'. This may be explained by the non-inclusion of other 'non-believing groups' in Top Ten's figure.

All surveys show the ratio of atheists to agnostics to be around 1:5 to 1:6. If one adds them to the other 'non-religious', they comprise the third largest group. Although their numbers are growing in the first world, the birth rates of the religious are significantly higher, particularly in Africa, Asia and South America. The pundits say that 'secularisation' has, relative to other beliefs, levelled out, while others predict growth in regions in which there are high 'defection rates'. In Islamic communities this is universally low while its 'conversion rate', mostly by marriage, is about half that of Christianity. In some places, to convert from Islam to Christianity may be lethal, a not-so-subtle deterrent! 2005-figures are:

Chinese traditional
Primal indigenous
African Traditional


'Secular' contains humanists, agnostics, atheists, deists, pantheists, freethinkers and those of no religion!

A deist is one who believes in a god by way of natural reason, sans revelation, while a pantheist is able to worship all gods, and sees 'God' as equivalent to nature or the universe. 'Freethinker' was commonly used in the 18th and 19th centuries to describe English 'dissenters', usually the wealthy and well-connected and who enjoyed the lively debate about the meaning of the increasing volume of scientific knowledge vis-a-vis religion. Charles Darwin and his circle referred to themselves as freethinkers.

The 'demography of beliefs' is a complex and specialised field. Making projections about 2050, as Stett has done while a useful exercise is somewhat fraught. One very knowledgeable person, with whom I had an email exchange, thought that Islam's numbers would not exceed Christianity's until near the end of the century.

I'm inclined to agree, having read many disparate bits of data and scrutinised divergent estimates by religious demographers, like the ones shown below (from Ontario-based consultant )

Author(s) Pop'n (bn) or % 2000 Pop'n (bn) or % 2025
John Gary
2.0 (Islam)
3.0 (Christian)
Samuel Huntington  20% (I) 30% (I)
30% (C)
Barrett & Johnson 1.22 (I)
2.035 (C)
1.89 (I)
2.711 (C)
World Chris. Encyc. 1.188 (I) 19.6%
1.999 (C) 33.02%

Todd Johnson 1.16 (I) 18.5%
2.09 (C) 33.4%
1.72 (I) 20.2%
8.023 (C) 35.5%

The World Christian Encyclopedia estimates for 2050 are:
Islam 2.229 (25%) and Christian 3.051 (34.25%)

Note: The World Christian Encyclopedia is authoritative and detailed, predicting that Christianity will slightly increase its 0.8bn 'lead' over Islam over the next 43 years. However, it also predicts a 2050 world population of only 8.909 billion.

The authoritative Encyclopedia Britannia Yr Book 2006 gives:

  • Muslim: 1.335bn (20.4%)
  • Christian 2.173bn (33.2%)
  • Hindu (in only 116 countries) at 0.871bn (13.3%).
  • The relative % growth rates and actual growth in numbers takes some 'untangling':
  • Muslim numbers, eg in Canada, Oceania or S. America, rise from a very small base, but at a high % growth rate. Islam is not the "fastest growing" in 75% of 238 countries.
  • There are Muslims in 206 countries but Christians in 238.
  • A current estimate of Muslim growth rates (Brother Andrew) gives 2.13% for Islam and 1.36% for Christianity (both below Stett's for the period 1989-2005).
  • More than one source puts Christianity as growing at the same rate as the world population, which in 2007 is 1.17%.
  • The most dramatic growth has been in Africa, with 10mn Christians in 1900 and 360mn in 2000! The % growth rates for Christianity exceed Islam's in Africa and Asia.
  • Stett tried to find the 'tipping point' when the number of Muslims would begin to exceed Christians, and predicted the year 2050.

    His calculation went awry, with the population of his three largest religions totalling 11.09 billion. As the US Census International Data Bank's estimate for 2050's world population is 9.404 billion, a 'scaling-back' is required. His numbers were too high and he didn't allow for the decline in the world's annual % growth rate:

    Year World Pop'n % Growth
    Annual Growth (mn)

    The formula used is r (t) = ln (P (t + 1)/ P (t))
    t = year
    r (t) = growth rate from mid-year to mid-year
    P (t) = population at mid-year
    ln = natural log
    I've not been able to come up with a 'tipping-point', but much of what I've read suggests that Islam may "reach numerical equality" later than 2050, given that it currently has 838 million fewer adherents, and that Christian numbers continue to grow.

    The Catholic Church's antipathy towards contraception will help cause an estimated 495 million growth in 2005-2050, with the biggest increases in the DR Congo, the Philippines, Mexico, Brazil, USA, Nigeria and Uganda. The third most populous nation, USA (currently 83% Christian), will have 433 million in 2050, while its % of Muslims is only just over 1% (3-4 million).

    India and Bangladesh are growing fast. Since India will be 1.592 billion, and Bangladesh 205 million in 2050, Stett's projected figure for Hinduism of 1950 million is excessive too. Currently India has about 100 million Muslims (13.1%) and Bangladesh, currently 147 million, has 117 million Muslims (83%) and 16 million Hindus (11%).

    One 2050 estimate has Muslims reaching 2.588 billion (33%), implying that it will have surpassed Christianity, and reaching 37% in 2100. Again, one should be wary of these figures, though it's supported by Samuel Huntington's 30%/30% cited above.

    Apart from India and Bangladesh, the most populous countries in 2050 will be (in millions) China 1392, the EU 435, USA 435, Pakistan 352, Nigeria 352, Brazil 253 and Ethiopia 212.

    Australia will be around 27 million. The world's fastest growing nation is Yemen (7.6% 2005-6) and in the Gulf nations it's 6.2%. The UAE averaged a growth rate of 4% for 1950-2005! The doubling time for these countries' populations is 12 years (6%) to 18 years (4%)!

    The median ages of world population were 20 years in 1900, 25 in 1995 and will be 42 in 2050, when the Less Developed Countries (LCDs) will comprise 80% of the world's people. Developed Countries comprise 1.2 billion now and will be 1.2 billion in 2050 (it would be lower but for immigration, mostly from Islamic countries).

    Fertility ratio is the average number of children per woman, with 2.1 children being replacement level. In the EU it's 1.40 while dominantly Islamic countries are over three times as high! (Afghanistan is 7.48, Pakistan 4.27, Iraq 4.8, Saudi Arabia 4.5 and much of North Africa 4.45). Fertility rates are declining in most LDCs, but are high in Asia 2.47, Latin America 2.55 and Africa 4.97.

    Research from several studies shows that the strongest predictor of the number of offspring is the "strength of religious affiliation of married women". Immigrants in Europe are more religious than the host population, and there's little loss of Islamic religiosity from one generation to another: fertility rates of Pakistanis and Bangladeshis in Britain have remained high, with low 'defection rates'.

    Muslim acceptance and action on contraception has been minimal. Muslim religious leaders are opposed, and that's unlikely to change. The world figure for contraceptive use is 53%, while in Somalia it's 1%, Chad 2%, Niger 4% and Afghanistan 4%.

    Islam's increase has already had an impact in creating religio-ethnic tension, conflict, terrorism and civil war in India, Kosovo, Bosnia, Chechnya, the Philippines and Thailand, leading to campaigns for secession. The UN reports that religious extremism and intolerance is on the increase, while 'Islamophobia' is prevalent in parts of the EU and elsewhere.

    European governments and communities face pressures created by dominantly Islamic immigrants, exemplified by the 2006 riots in France. In some host nations, such as Australia, there's a non-racist concern for being 'overwhelmed' by Islamic immigrants, and the large difference in fertility rates.

    If or when the Christian world finds itself in second place is a conundrum I've been unable to resolve, as there appears to be little agreement amongst those who've 'done the maths'

    References and sources

    Prof Philip Jenkins is the best of the academic commentators,

    Brother Andrew is unhappy with mythmaking Islamic predictions at,ca/islammyths-fastest-growing.htm

    World Christian Encyclopedia (2001) D A Barrett

    How to Slow the Population Clock