A new study by the Pew Research Center shows Christianity on the decline in Europe.
A century ago, Christians made up nearly two-thirds of the population in European countries. But that number has dropped dramatically, with Europe now home to one-fourth of the world's Christian population.
At the same time, Christianity is growing dramatically in Africa and elsewhere.
Today, Christians make up a quarter of Africa's population, though few live in North African countries.
More than one third of the world's Christians live in the Americas, while the Mideast and North Africa have the smallest Christian populations.