Christianity

Mexico is home to not only the largest Spanish-speaking population in the world, but one of the biggest Catholic populations, too.

In the last two decades, several religious groups have moved to allow same-sex couples to marry within their traditions.

Millennials are less religious than older Americans and less likely to identify with a religious group, and those traits are reflected in the way they celebrate Christmas.

Acceptance of homosexuality is rising across the broad spectrum of American Christianity, including among members of churches that strongly oppose homosexual relationships as sinful.

Religious institutions are starting to formally address the participation of transgender people in their congregations, much as they have with the issue of accepting homosexuals.

The three countries on the pope’s itinerary -- Uganda, Kenya and the Central African Republic -- all have sizable Catholic populations. But they also have seen violent clashes in recent years.

Some of the largest Christian denominations in the U.S. have relatively low levels of involvement among their members.

The vast majority of Americans still believe in God, but there are strong signs that many are less certain about this belief than in years past.

Making up just 0.5% of U.S. adults, Seventh-day Adventists are extremely devout and are one of the country's most diverse religious groups by race and ethnicity.

There has been a modest drop in overall rates of belief in God and participation in religious practices. But religiously affiliated Americans are as observant as before.