By 2050, the number of Muslims worldwide will grow by 70 percent, outpacing every other religion and matching Christianity as the world’s most numerous faith. That rate of growth means that by midcentury, one in 10 people in France, Germany, Italy and Britain will be Muslims.

That’s according to a Pew Research Center study out Thursday, which looked at the age distribution, fertility and mortality rates, and patterns of migration and conversion of the world’s religious groups. The study projects that by 2050, 30 percent of the global population will be Muslim — all but equal to the 31 percent that Pew projects will be Christian. An additional 15 percent will be Hindu, 5 percent Buddhist and 0.2 percent Jewish.

That shift will be especially pronounced in Western countries, many of which will see the share of their population that is Muslim double, and in some cases triple, over the course of just two generations.

In a perfect world, that trend would be welcomed as an addition to the rich diversity of cultures and beliefs that make up any pluralistic liberal society. In practice, it will probably increase the strain on countries whose self-image of tolerance has clashed with the reality of lingering prejudice and unease toward people who are different.

Take Italy, where two of three respondents told Pew last year that they have unfavorable views of Muslims, and the government of the Lombardy region passed regulations in January that restrict the building of mosques. Managing those tensions will only get more important: The share of Italy’s population that is Muslim is projected to roughly triple, to 9.5 percent, by 2050.

Or Germany, where a court last month lifted a ban on teachers wearing headscarves, yet marches by the anti-Muslim group Patriotic Europeans Against the Islamization of the West draw thousands of supporters. The share of Germany’s population that is Muslim is projected to double, to 10 percent, by 2050.

Or France, where a Muslim woman told a BBC reporter after the Charlie Hebdo shootings that being rejected by her country because of her faith is “like being rejected by your mother,” and others said the French “would rather we have blond hair and blue eyes.” The share of France’s population that is Muslim is projected to increase 45 percent by 2050.

Or Canada, where Prime Minister Stephen Harper told Parliament last month that the niqab is “rooted in a culture that is anti-woman.” His government is fighting to prevent immigrants from wearing the niqab while taking their oaths of citizenship. The share of Canada’s population that is Muslim is projected to almost triple by 2050.

Those divisions and prejudices may have been inflamed by the rise of Islamic State, the attacks in Paris, the flood of refugees from Syria, a weak economy and any number of other challenges. But prejudice — whether its targets are Muslims, Jews or any other religious group — doesn’t need much of an excuse. If Pew’s projections are right, countering that prejudice is going to get more important.

Christopher Flavelle writes editorials on health care, economics and taxation for Bloomberg View. For more columns from Bloomberg View, visit http://www.bloomberg.com/view