Earlier this month the Pew Research Centre released data from its Global Religious Futures project, which forecasts the changing size of eight major religions over the next half century.
The study is based on demographic factors in 198 countries including fertility, age and life expectancy.
Here's what we learned:
1. By 2050 there will still be more Christians than any other religious group
The global Christian population will remain stable over the next 35 years, despite Muslims being the fastest-growing religious group. Islam is forecast to be the world's largest religion by 2070, if current trends continue.
2. More and more Christians will be living in sub-Saharan Africa
Mainly at Europe's 'expense'.
3. Atheism is on the rise in the West, but not worldwide
Mainly due to ageing populations and low fertility rates in countries such as Japan and China.
4. Christianity will 'shrink' in the US
Although total numbers will increase, by 2050, two-thirds of Americans will be Christians, as opposed to three-quarters in 2010. In addition, over the next 35 years, Islam will replace Judaism as the second most-prevalent religion (although the biggest increase will be in the number of people with no religion).
5. Christianity will be a minority religion in the UK by 2050
With more and more people likely to have no religion at all.
More: [The importance of religion around the world in five charts]2