There is a passage in Augustine, found in Of Christian Doctrine during his discussion of the order of love, where he argues that,
since you cannot do good to all, you are to pay special regard to those who, by the accidents of time, or place, or circumstance, are brought into closer connection with you.
Stephen Wolfe, for example, cites this exact passage in his book and only this portion of it, on which more in a moment. He uses it to support this particular claim:
The in-group/out-group distinction, which prioritizes concern for one's own people and native soil, troubles many in the West, at least when Western ethnic-groups begin to distinguish themselves in this way. Christians will ask, 'Aren't we called to love all equally?' assuming the affirmative answer is obvious. But despite modern Christian sentiment, a quick glance at the Christian tradition (and mild reflection on one's own relationships) reveals the almost ubiquity of the opposite view—that the intensity of love varies by degree according to similarity and the extent that another is bound to you.
Wolfe then quotes that portion of Augustine. They take the argument to be that Augustine's use of the orders of love endorses the notion that we owe a unique obligation to those who are closest to us which supersedes the obligations we owe to those further away. This, then, becomes their basis for arguing that giving preference to one's "own kind" (read: ethnic or racial group) is actually in agreement with the Christian tradition.
The trouble is these Christian Nationalists have Augustine almost entirely backwards. The context of the above passage is Augustine's reflection on the broader question of love for neighbor. The argument Augustine is making runs in almost the exact opposite direction from where Wolfe and his allies are trying to take it.
To begin, Augustine is quite clear that we are called by God to love everyone. So there is no trace here of any idea that we owe love to some and not to others, which is the subtext of much white Christian nationalist discourse. But then we need to attend more carefully to the reasons Augustine offers for why there is an ordering to our loves, such that we can be said to owe certain specific duties to some people that we do not owe to others.
The white Christian nationalists think this ordering is grounded in kinship, common culture, ethnicity, and so on, as Wolfe explains in the excerpt above. The ethnic ties are the grounds not only for our acts of love, but even for the feelings we have toward a person. But that isn't even remotely how Augustine anchors his argument.
Here is the fuller context of the quote Wolfe very selectively excerpted in his book:
Further, all men are to be loved equally. But since you cannot do good to all, you are to pay special regard to those who, by the accidents of time, or place, or circumstance, are brought into closer connection with you. For, suppose that you had a great deal of some commodity, and felt bound to give it away to somebody who had none, and that it could not be given to more than one person; if two persons presented themselves, neither of whom had either from need or relationship a greater claim upon you than the other, you could do nothing fairer than choose by lot to which you would give what could not be given to both. Just so among men: since you cannot consult for the good of them all, you must take the matter as decided for you by a sort of lot, according as each man happens for the time being to be more closely connected with you.
In other words, for Augustine the test is not shared ethnicity or culture, but rather simple proximity—which is regarded as a kind of "accident" of time and place ordained by providence. The reason for the order of love is not grounded in ethnic solidarity, but in simple human finitude. We do not have infinite resources of time, energy, or money, and so when we consider who we owe those resources to as acts of neighborly love, it is reasonable to regard those who live closest to us as the proper outlet for those kindnesses simply because providence has placed them in front of us. But the test is actually proximity, not ethnicity.
To give the matter some teeth, Augustine would say that a white Christian who lives in Baton Rouge actually owes more to his Black neighbors living ten minutes away in the city than he does to, say, white people living a day's drive away in rural North Carolina. This is because there is no basis in Christianity for saying "I should love the person who shares my ethnicity and lives far away more than I love my immediate neighbor down the street who is of another ethnicity." That, after all, is one of the chief points of the Good Samaritan passage, a passage Augustine invokes during this discussion. The source of Wolfe's ideas about ethnicity come from elsewhere.
But we should continue. Augustine's argument, in short, is that Christianity demands that we love everyone, but due to human limitation, we often are only able to show specifics acts of love or mercy toward our neighbors.
But even here he presses the point further by saying that even the angels should be regarded as our neighbor since angels sometimes show mercy toward us. This means that every person is our neighbor because every person is theoretically capable of giving or receiving acts of mercy from or to ourselves. He then turns to St Paul to give the argument even greater force:
And so also the Apostle Paul teaches when he says:
For this, You shall not commit adultery, You shall not kill, You shall not steal, You shall not bear false witness, You shall not covet; and if there be any other commandment, it is briefly comprehended in this saying, namely, You shall love your neighbor as yourself. Love works no ill to his neighbor.Romans 13:9-10 Whoever then supposes that the apostle did not embrace every man in this precept, is compelled to admit, what is at once most absurd and most pernicious, that the apostle thought it no sin, if a man were not a Christian or were an enemy, to commit adultery with his wife, or to kill him, or to covet his goods. And as nobody but a fool would say this, it is clear that every man is to be considered our neighbor, because we are to work no ill to any man.
In other words, if we read Augustine's concept of the orders of love as saying "some people are our neighbors and others aren't and we only owe love to the first group," we make Paul absurd. For Paul treats the entirety of the decalogue as being a summation of what it means to love neighbor—and if there are any people we can regard as not being our neighbors, it therefore follows that there are people we can commit adultery with or even murder. Since that is obviously absurd, we rightly regard everyone as our neighbor.
In other words, while there may be reasons of physical limitation that prevent us from loving everyone in the same way, we are called to love everyone and to regard all people as our neighbors. Where we must distinguish between who we owe specifics acts of mercy to, the test is not ethnicity, but simply who God has put in front of you in that moment through the accident of time and place.