If you know the story of ancient Rome, then you know how the emperors attempted to extirpate Christianity. You will also likely know that eventually, since Rome could not stomp it out, Christianity became the religion of Rome under Constantine. This is the same Rome that also crucified the Messiah through its political system. This is also the same Rome that produced a "Beast" of a man through Nero.
Modern Rome, if we want to call American Politics by the name, is having a little miniature crisis from this link over at Mother Jones:
This tweet illustrates a basic component of Christian nationalism: spiritual warfare. That’s the notion that all that transpires in our world is a manifestation of the mammoth and eternal clash between God and Satan. The tussle over abortion is not an argument between fellow citizens with conflicting views on bodily autonomy or the question of when life begins; it is a battle between Jesus and Lucifer. Consequently, those who support reproductive freedom are demons or, at the least, in league with or controlled by demons.
Wolfe contends that Americans who champion reproductive rights are doing so as a ritual sacrifice to Molech, who in the Bible appears to be a Canaanite god (though there’s disagreement among scholars over who or what Molech is). And he insists that passing LGBTQ protections is a form of praying to Baphomet, a deity that the Knights Templar, a Catholic military order active early in the second millennium, were accused of worshipping that later became associated with the occult. (You might recall the Knights Templar from The Da Vinci Code and the Indiana Jones movies.)
Does one need to be a Christian Nationalist to believe in Good and Evil? The answer is a clear no. Platonists, for example, believe in a Form of the Good. This implies, then, that there is a form of the "not so good". The definition is here conflated with religion. If people that are liberal are afraid of ideas of Good and Evil, then the problem is not one of Christian Nationalism alone. It is instead a problem of relativism which is more a characteristic of socialism or ideologies that believe in little when it comes to spiritual precepts.
As far as abortion goes, killing the unborn is not, and never has been a political topic. There is no such thing as reproductive freedom since people are not Xerox machines. There is a decision that can be made regarding the germination of life, though. Quite often, this is done in a way with no consideration for this life other than by one person. What do you call that? Sounds like potential evil if it is done for "reproductive freedom"--whatever that means. Indeed, demons are going to love these kinds of decisions in a Christian worldview. (Murder, incidentally, is also a decision made by only one party to end the life of another without consulting them)
Why is this a good thing? Well, not to beat a dead horse, but in the End of Days it is said people will not be able to recognize good from evil and in fact will call evil good. If this is not a sign of such a thing, it would be hard to find a more definitive one. Believers can be heartened that their redemption must be drawing nigh. For everyone else, keep on believing in the Good. Don't let sloppy relativistic arguments wearing the title of Christian Nationalist trip you up.