"My kingdom is not of this world. If My kingdom were of this world, then My servants would be fighting so that I would not be delivered over to the Jews; but as it is, My kingdom is not from here." John 18:36
"For our citizenship is in heaven, from which also we eagerly wait for a Savior, the Lord Jesus Christ." Philippians 3:20
"Beloved, I urge you as sojourners and exiles to abstain from fleshly lusts." 1 Peter 2:11
If you presented your ideas of "Christian Nationalism" to the early Christians (A.D. 70-313), they would have condemned you as a heretic. They refused everything nationalistic. They understood they were merely sojourners here on Earth and citizens of Heaven. Observe what these early Christians had to say about Patriotism:
"We have no country on earth. Therefore, we can despise earthly possessions." —Clement of Alexandra (c. 195, E)
"All zeal in the pursuit of glory and honor is dead in us. So we have no pressing inducement to take part in your public meetings. Nor is there anything more entirely foreign to us than the affairs of state. We acknowledge one all-embracing commonwealth—the world." —Tertullian (c. 212, W)
As for you, you are a foreigner in this world, a citizen of Jerusalem, the city above. Our citizenship, the apostle says, is in heaven." —Tertullian (c. 212, W)
[Lucilius, a Pagan:] "It is virtue to give that which is really due to honor. . . . That is, we should consider the interests of our country first, those of our parents should come next, and our own interests should be in the third and last place." . . . [Lactantius's Reply:] "However, we will presently see how false these things are. . . . It is a virtue to restrain anger, to control desire, and to curb lust. For this is to flee from vice. For almost all things that are done unjustly and dishonestly arise from these affections. . . . Also, if desire is restrained, no one will use violence by land or by sea. Nor will anyone lead an army to carry off and lay waste the property of others. . . . it is not virtue, either, to be the 'enemy of the bad' or 'the defender of the good.' . . . When the agreement of men is taken away, virtue has no existence at all. For what are the interests of our own country, but the hardships of another state or nation? To extend the boundaries that are violently taken from others, to increase the power of the state, to improve the revenues—all of these things are not virtues, but the overthrowing of virtues." —Lactantius (c. 304-313, W)
"How can a man be just who hates, who despoils, who puts to death? And those who strive to be serviceable to their country do all these things." —Lactantius (c. 304-313, W)
"He is extolled with praises to heaven who gains these "goods" for his country! I speak of one who has filled the treasury with money by the overthrow of cities and the destruction of nations. In him there is said to be the greatest and most perfect virtue! And this is the error—not only of the people and the ignorant—but also of the philosophers." —Lactantius (c. 304-313, W)
"When they speak of the 'duties' relating to warfare, their speech pertains neither to justice nor to true virtue. Rather, it pertains only to this life and to civil institutions. And this is not justice." —Lactantius (c. 304-313, W)
When Rome kept getting more and more sinful and was basically going to Hell in a hand basket, the early Christians never had the idea to fight to preserve their nation. This applies whether the nation is a "God fearing" nation or not. They refused to join the military because it violated their beliefs against war and violence. If they were in the military when they converted, they sought other positions where they did not have to violate their conscience, while serving out their time.
As you can see, the early Christians have much to teach modern "Christians" who reject the words of Jesus while taking them as mere suggestions rather than commands. It is no wonder the modern "Church" is in the condition she is.
Christians are not called to "combat evil." Find one single verse in the New Testament to to support this fallacious concept that you have not proof texted by ripping it out of its immediate context. Hint: You won't find one!
American "Christianity" is a joke. These "Christians" are quick to pick up arms, and are itchy for war. They know nothing of the Jesus of the Bible and the words He spoke. North American and European "Christians" need to discover the true Jesus of the Bible and conform themselves to His words. Their attitudes and behaviours are conformed to the teachings of Augustine, Luther, and Calvin as opposed to that of Christ.
Repent, and do the works Christ would have you to do! Prove your faith by your deeds!
"Obedient faith is that which saves." —John Owen
P.S.: Moreover, observe this statement:
"Treason is falsely laid to our charge, though no one has ever been able to find followers of Albinus, Niger, or Cassius among Christians. . . . A Christian is enemy to no one—least of all to the emperor of Rome, whom he knows to be appointed by his God. So he cannot help but to love and honor him. And the Christian must necessarily desire his well-being, along with that of the empire over which he reigns—so long as the world will stand, for so long as that will Rome continue. To the emperor, therefore, we render such reverential homage as is lawful for us and good for him. We regard him as the human being next to God, who from God has received all his power. He is less only than God. . . . Being only less than the true God, he is greater than all others." —Tertullian (c. 212, W)
Did you "Christian" Nationalists do this with Barack Obama? Are you doing this with Joe Biden? The Christian is to have zero hate for anybody, including people like Joe Biden. Joe Biden was appointed by God. Do you pray for him? Do you pray for the whole of America under his rule? If you do not resemble what the early Christians describe, then are you a Christian in the least? If you were, the early Christians would call you spiritually weak and ignorant as to the teachings of Jesus and His apostles.