America has long prided itself on being a country where people can choose whatever religion they like. The majority has long chosen Christianity. By 2070, that may no longer be the case. If current trends continue, Christians could make up less than half of the population — and as little as a third— in 50 years. Meanwhile, the so-called nones — or the religiously unaffiliated — could make up close to half of the population. And the percentage of Americans who identify as Muslims, Jews, Hindus, Buddhists and other non-Christian faiths could double. Those are among the major findings of...