Christians are by far the largest religious group on the planet, and the religion has gone truly global over the past century, according to a new report out Monday, which finds some of the world's biggest Christian communities in surprising places.

Europe was the clear center of world Christianity one hundred years ago, but today the Americas are home to more than a third of all Christians. In fact, the United States has the world's largest Christian population, of more than 247 million, followed by Brazil and Mexico.

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