[I want the USA back]

There is no establishment of religion, so this is not a Christian nation.
However, some people, ignorant of the meaning of words, call it a Christian nation because the majority of the people are nominally Christian.

[fwdude]

It is a Christian nation because it was founded under the presumption that rights are granted from God; and it is beyond dispute that the Founders were unambiguously referring to the God of Christianity and all of Scripture.

[conservatism_IS_compassion]

There is no establishment of religion, so this is not a Christian nation.

However, some people, ignorant of the meaning of words, call it a Christian nation because the majority of the people are nominally Christian.

The US is officially not a Christian theocracy. OTOH, the US is officially not antiChristian, either. There can be a Christian theology which opposes theocracy, whether Christian or not. In fact, The Baptist Faith and Message - a pamphlet of the Southern Baptist Convention - takes exactly that position. By that standard, the US is about as Christian as a country can be.