There's a lot to unpack here, but the thing that gets me is that "Christian nationalist, " setting aside that people do use the term as a pejoritive, and can be interpreted by some as synonymous with white supremacy, in the normal sense of the term, it actually is an oxymoron.
The central aspect to Christian identity is briefly acknowledged as a breezy aside: "- though Christ's kingdom is not of this world-" ...and no more is said of that. It's just sort of waved away, because the author really wants to make the case that Christian nationalism is really quite noble and good, the USA really should be the most completely Christian nation on earth, but those darned atheists and liberals just want to disenfranchise and persecute us.
But what about the part that is so quickly passed over: Christians are first and foremost citizens of the Kingdom of God. Why then so focused on worldly matters? Does Jesus call us to create a Christian nation on earth?
Does a citizen of the Kingdom of God hang appeal to heaven flags outside their office, or wear an AR15 pin on their lapel?
This is not about Christians at all. Christians expect persecution, and in response they pray for their persecutors, they don't write defiant opinion pieces in publications financed by men in expensive suits. No, this isn't about Christians, It is a trick, it is a scam: this is the propaganda of wolves. Matt 7:15