Your definition is incoherent with your first sentence, then. If Christian nationalism is simply the desire to live in a Christian nation, exclusive of coercion, then it is absolutely a political force to be reckoned with. That definition probably covers a huge chunk of evangelicals, mainline protestants, catholics, and the orthodox.
Anyway I do think the topic could be beneficial if people actually talk about what "nation" means. Contra B-1 83 above I do think that the first definition - "one nation or nationality above all others...its cultures and interests..." etc - has a strong racial aspect to it.
We moderns in general and Americans in particular have really odd notions about "nation" that are completely unique to the last few centuries in mankind. They are informed by our novel formation as a society built from multiple nations, a kind of alloying of peoples. We then tend to think of the "nation" in the sense of the state, the authority structure that governs the physical place where that mixture of people resides. In that sense, "nation" has an identity relationship with the US. But that's basically no definition at all - that means there's no such thing as the culture of the United States in any kind of permanent sense. There can't be, because that offers no positive or affirmation of what that culture is other than a statement of fact: whatever we see when we look, that is what it is. From that view you can't argue against what the nation of the United States is or even should be - it is whatever it is. That means if the US becomes 90% Indian, there is the US culture.
Contrast that to every single "old world" country. They formed precisely the other way around - a group of families, forming clans, forming tribes, forming nations settled in places, and their governing bodies became the authority structure over that place. The relationship between authority and tribe is inverted. In the modern era this is less clear, and the lines are much less fluid, but the further back you go in time the more explicit it is, and you don't have to go back very far to begin to see it. Here is a map of Europe in the 1700s:
Of course what we lump in as "French" or "Germans" today is an amalgamation of many, many ancient tribal nations. For example, even France itself wasn't anywhere near unified in French-speaking in the late 1800s - several major areas were fully non-Francophone speaking languages like Breton, Basque, Gascon, or Alsatian.
If we use the word "constitute" in its original sense, that would be something like "what makes a thing have being" or "what gives an idea body". To me what constitutes a nation must be the people in it, not the governing structure over it. I think our modern notion of "nation" having an identity relationship with "state" rather than it's true sense of the
people is simply wrong. After all, ethnos is the Greek for nation, where we get ethnicity; nation is from Latin natio meaning birth, meaning people with a common ancestry.
On the other hand, over against how we use it today, the ancient mind had only vague notions of heritability and no concept of genetics as such. Ethnos was not about genetic inheritance or the modern idea of race but was instead something to which you were identified by your way of life. Your nation, your
ethnos, was something you were a part of because of how you lived, what the Greeks called your
nomos. This was an expansive concept that would cover our modern notions of law, religion, culture, and traditions - because in the ancient world the boundaries between these things for the most part simply didn't exist. Our concept of naturalization, though, would have been very acceptable to them - but would have little to do with sworn fealty to a state apparatus, and
everything to do with changing how you live your life.
Turning back to the US, then, this doesn't really help us. We are a state comprised of people from many nations. How can we be one nation? In what sense?
You could say - loyalty to the state. This is basically what western democratic societies have done. But this absolutely
requires a shared idea of the state, what its purpose is, what it should and shot not do. Or the state becomes malleable in the hands of a changing body politic. I mean, this is kind of the point of a democratic system, right?
So we have to go back one step further: loyalty to some ideal or philosophy or set of ideals upon which the state's governing authority rests. Here we can find a universal principle, because this is no different than what Aristotle said was the purpose of the state. He said that ideal was living well, achieving the good life (not merely mutual defense or exchanging goods), through noble actions (not merely living in common), and therefore was ultimately about the practice of virtue. To him the state arose from the family and tribe because these are the same things families and tribes can bind together.
What is the ideal or philosophy or set of ideals upon which the authority of our state rests? Because fealty to
that is what will define a person as a true American. That is what creates an ethnos, a nationality, in the true sense. And that is the only way you safeguard against completely losing the plot, going off script, and having your state become a tool in the hands of whatever genetic-ethnic tribal affiliation currently has the most power. (The above should explain why "western democratic societies" continually fail when they're planted, like in the middle east. It obviously can't be loyalty to the state apparatus or structure of the government, or else Liberia or Syria would be coherent states; let the reader understand.)
