I don't know if Christian nationalism is bad, but I'm not sure there is support for it. I am fairly certain there is nowhere in the Bible that says, "It is OK if people of other nations suffer since they are not in your nation".
Reading Tuchman's book on the middle ages, it is amazing what all has changed. For example, at that time it was a sin to boast that your product was better than someone else's. That was being prideful.
That thought would destroy modern consumerism. Heck, far more recent, Lincoln tore his name off his ballot to show people that he did not vote for himself as that would be prideful.
Of course, it was popular to wear sackcloth and self-flagellate in the middle ages to prove one was righteous. Some modern movements believe one must have conspicuous consumption to show God favors them. Amazingly, in France in the Middle Ages, even working extra hours to make more money was considered sinful (though I am not sure she said which sin, maybe greed).
So I am not sure which of the myriad of interpretations is right. I have mine. It may be Christian Nationalism is the right interpretation, I'm just not sure I see the support for it.