Another poll, the American Religious Identification Survey, found that 15 percent of Americans now claim no religious affiliation, nearly double the percentage in 1990.
Those figures suggest that Christianity is on the decline. Yet it remains a major force in American life: More than three in four Americans identify as Christians, and religion – Christianity in particular – is connected to many aspects of our lives.
It influences the debate over social issues and plays an important role in many families and communities; it touches everyone from death row inmates to the president, who Monday oversaw the traditional White House Easter Egg roll.
So is the United States, in the end, a "Christian nation?" And what does that mean, anyway? President Obama, as part of an effort to reach out to the Muslim world, explicitly rejected the formulation in Turkey last week.
"We do not consider ourselves a Christian nation or a Jewish nation or a Muslim nation," he said. "We consider ourselves a nation of citizens who are bound by ideals and a set of values."
Not that the president is averse to using Christian imagery: In what the White House billed as a "major" speech Tuesday, the president invoked a parable from the Sermon on the Mount.
"As crucial as religion has been and is to the life of the nation, America's unifying force has never been a specific faith, but a commitment to freedom—not least freedom of conscience," he wrote.
Newsweek polling found that 62 percent of Americans believe theirs to be a Christian nation – which, despite being down from 69 percent last year, is a formidable number.
Yet the separation of Church and state remains relatively strong. Despite the efforts of many Christian evangelicals, prayer is generally kept out of schools, as is, by and large, the teaching of Creationism. The popular elected president supports abortion rights. And on one of the key social issues of the moment – gay marriage – the traditional Christian perspective appears to be losing ground, with increasing support for gay rights among the young and more states legalizing same-sex marriage.
Yet Americans, more generally, are not "timeless in our beliefs," as evidenced by a consistent pattern of social change virtually since the nation's founding. Perceptions about everything from slavery to alcohol to women's rights have changed dramatically over the years.
Ultimately, the question of whether America is a "Christian nation" depends in large part on how you define the phrase. If a "Christian nation" is simply a nation made largely of Christians, then America is undeniably one. Despite the increase in non-religious Americans, they are still outnumbered more than 6-1 by Christians, according to Gallup.
But if a "Christian nation" is something else – a nation on which laws, behavior and policy are fundamentally tied to Christian ideals – then the question is more complex. The legal system has an undeniable basis in the Christian conception of morality, as does our societal conception of right and wrong.
Yet the phrase "Christian nation" can also be problematic. Domestically, it suggests the possible sublimation of individual rights in favor of a unified and inflexible worldview. Internationally, it creates an "us vs. them" as the U.S. fights for hearts and minds in countries with overwhelmingly Muslim populations.
There's much more to discuss on the issue, of course. But we're leaving the rest to you. Do you think the United States is a Christian nation? How do you define the phrase? And do you believe that it's useful? Let us know below.