Islam is the only religion growing faster than the world's population, and it will be the largest in the world by 2070, research has found.

US-based Pew Research Centre analysed demographic change among the world's major religions and found that the world's population of Muslims will grow by 73 per cent between 2010 and 2050, compared to 35 per cent for Christians, the next fastest-growing faith.

The world's population will grow by 37 per cent over the same period. If those rates of growth continue past 2050, Muslims will outnumber Christians by 2070, the report found.

It also says that Muslims will make up 10 per cent of Europe's population.

In 2010 there were 1.6bn Muslims in the world, and 2.17bn Christians. By 2050, there will be 2.76bn Muslims and 2.92bn Christians - and if both religions continue at that rate of growth, Islam will have a larger number of followers than Christianity by 2070.

Atheists, agnostics and non-religious people will decline from 16.4 per cent of the world's population to 13.2 per cent by 2050, the report added, despite growing in Europe and North America.

The changes are partly due to the various fertility rates each religion has. Muslims have the highest, at 3.1 children per woman, followed by Christians, at 2.7.