As I mentioned before, the school prayer scenario and numerous other scenarios where believers either force everyone else to declare their religion or at least try to pry it out of them combined with their very often, and sometimes not so subtle, demands that we shut up about our disagreement tells us one thing very clearly: The believers want us to conform and will accept nothing else.
In recent years, one hears more and more people saying, in all seriousness, that the U.S. is a "Christian nation". This is a recent development. Prior to the last 10 or 15 years, one didn't hear that except perhaps in Western History classes where it was meant explicitly to refer only to the fact that many of the settlers of the U.S. were Christians or from countries in the part of the world considered Christian. Even in that context, it was unusual to hear such a thing.
What one heard instead, as the commonly accepted characterization of the U.S. was: This is a free country.
I think it is telling that "this is a free country" has been replaced in the minds of many with "this is a christian nation". Those who have done this have, unknowingly I suspect, juxtaposed the two choices facing us: Freedom or theocracy.
Whenever you hear this sort of "christian nation" nonsense, I suggest that you say:
"No. This is a free country."
You can follow that with this:
"If you don't like living in a free country, perhaps you should leave. There are many countries that have theocracy instead of freedom. You should move to one of those."