Islam is the fasting growing religion in the world, and will be the largest in the world by 2070, new research suggests.

A study updated this week by the Pew Research Centre titled 'Muslims and Islam: Key findings in the US and around the world', suggests that Islam will grow by 73 per cent by 2050, compared with only 35 per cent growth for Christianity.

The entire world population is expected to grow by 37 per cent, meaning Islam will grow at nearly twice the rate of the world. In 2010 Christians numbered 2.17 billion, and Muslims 1.6 billion. By 2070 those numbers will reach 2.92 billion and 2.76 billion respectively.

In the US, Muslims are predicted to make up 2.1 per cent of the population by 2050. They currently make up approximately 1 per cent of the population, numbering around 3.3. million. In Europe, Muslims will reach 10 per cent of the population by 2050.

Atheism and non-religious identification will decline, the report says. While such groups will grow in North America and Europe, globally they will decline from 16.4 per cent of the population to 13.2 per cent by 2050.

The reports suggest two factors behind Islam's rapid growth. Muslims have the highest fertility rate, at 3.1 children per woman. Muslims also have the youngest average age – 34 per cent are aged under 15. 

The reports suggests that most people in majority Muslim countries have an unfavourable view of ISIS. Often, people in predominantly Muslim countries were as concerned about the threat of Islamic extremism as those in the West.