It’s official: Europe is becoming less Christian.

An international study of demographic trends shows that Europe’s Christian population is expected to shrink by about 100 million people in the coming decades, dropping from 553 million in 2010 to 454 million in 2050.

While Christians will remain the largest religious group in Europe, they are projected to drop from three-quarters of the population to less than two-thirds.

By 2050, nearly a quarter of Europeans (23 per cent) are expected to have no religious affiliation, and Muslims will make up about 10 per cent of the region’s population, up from 5.9 per cent in 2010.

The figures have been published by the Washington-based Pew Research Center.

They show that in the five years 2010 to 2015, deaths outnumbered births among Christians in 24 out of 42 European countries in a pattern that is set to continue. In Germany alone, there were an estimated 1.4 million more Christian deaths than births in the five year period.

Eight European countries, including Ireland, however, bucked the trend with increases of at least 10,000 in births over deaths in each case. The other seven countries were France, Spain, Luxembourg, Switzerland, Poland, Norway, and Finland.

In contrast, among Muslims there was no European country where the number of deaths exceeded births over the same five year period. In Germany, the UK, Italy, Russia and France, there were at least 250,000 more Muslim births than deaths in each country over the period.

The lower average age of Muslims in Europe - 33 as opposed to 43 for Christians - is said to be a factor along with higher fertility rates.

Among the religiously unaffiliated (atheist, agnostic, no particular religion) deaths outnumbered births by at least 10,000 in Austria, Ukraine and Russia but this group saw either a natural increase in 19 countries or little change in 20 countries between 2010 or 2015.

This reflects the relatively young age profile of the religiously unaffiliated compared to Christians in Europe.

Europe is the only region in the world where the total population is projected to decline by 2050.

Worldwide, it is projected that within 20 years babies born to Muslims will modestly exceed births to Christians.

Between 2010 and 2015 births to Muslims were 31 per cent of babies born worldwide, far exceeding the Muslim 24 per cent share of the world’s population.

In recent years 33 per cent of the world’s babies were born to Christians, slightly more than the 31 per cent Christian share of the world’s population in 2015.

Over the same period Christians had a disproportionately large share of the world’s deaths, at 37 per cent.

A relatively young Muslim population with high fertility rates has led to a projection that between 2030 and 2035 there will be slightly more babies born to Muslims (225 million) than to Christians (224 million), even though the Christian population will still be larger.

By the 2055 to 2060 period however, the birth gap between the two is expected to approach six million - 232 million births among Muslims to 226 million births among Christians.

Internationally, Pew Research forecasts that there will be near parity between Muslims (2.8 billion, or 30 per cent of the global population) and Christians (2.9 billion, or 31 per cent) by 2050.