We can see from what has been said thus far that in the broadest sense goodness itself is one’s neighbor, since people are neighbors according to the nature of the good that they do, which they get from the Lord. Further, since goodness itself is one’s neighbor, love is one’s neighbor, because everything good is a matter of love. This means that any individual fulfills the role of a neighbor according to the nature of her or his love, which is the Lord’s gift.
It is obvious from people who are mired in love for themselves that love is what makes someone a neighbor and that we are neighbors depending on the nature of our love. Such people recognize as neighbors those who love them the most—that is, those who are most “their own.” These they embrace, these they kiss, these they benefit, and these they call kindred. They accept others as neighbors to the extent that they receive love from them, depending therefore on the quality and amount of the love. People like this start with themselves to determine who is their neighbor, because it is their love that makes their neighbor and determines who it is.
People who do not love themselves above all, though (like all who are in the Lord’s kingdom), start in determining who their neighbor is with the one whom we ought to love above all—that is, with the Lord—and they accept people as neighbors depending on their love for and from him.
This makes it quite clear where we of the church should start in deciding who our neighbor is, and shows that people are our neighbors depending on the goodness that comes from the Lord—that is, on the basis of goodness in itself.
Furthermore, in Matthew the Lord tells us that this is true:
He said to the ones who had been engaged in doing good that they had given him something to eat, that they had given him something to drink, welcomed him, clothed him, visited him and come to him in prison, and then said that to the extent that they had done this to one of the least of his family they had done it to him. (Matthew 25:34–40)
These six good deeds, understood spiritually, comprise all the kinds of neighbor.
This also shows that when we love what is good we are loving the Lord, because the Lord is the source of what is good, the one who is devoted to what is good, and the one who is the good itself.
However, it is not just people as individuals who are one’s neighbor but people in the plural. That is, it is any smaller or larger community, our country, the church, the Lord’s kingdom, and above all the Lord himself. These are “our neighbor,” to whom we should do good out of love.
from Regeneration, Pages 10, 11