From Pew Research: Overall, six-in-ten U.S. adults – including nearly seven-in-ten Christians – say they believe the founders “originally intended” for the U.S. to be a Christian nation. And 45% of U.S. adults – including about six-in-ten Christians – say they think the country “should be” a Christian nation. A third say the U.S. “is now” a Christian nation.
At the same time, a large majority of the public expresses some reservations about intermingling religion and government. For example, about three-quarters of U.S. adults (77%) say that churches and other houses of worship should not endorse candidates for political offices. Two-thirds (67%) say that religious institutions should keep out of political matters. Only 31% of those who say that the U.S. shoudl declare itself a Christian nation think that separation of church and state should be abolished. (Go here.)
63% of Americans self-identified as Christians in 2021, down from 78% as recently as 2007. Protestants over that time declined from 54% to 40% of the entire population, while Catholics held relatively steady, 24% to 21%. (Go here.)