First of all, I need to define “neighbor.” After all, this is the one we are called upon to love and the one toward whom we are to extend our goodwill. You see, unless we know what “neighbor” means, we may extend goodwill in basically the same manner indiscriminately—just as much to evil people as to good ones, then, so that our goodwill is not really goodwill. That is, evil people use their generosity to do harm to their neighbor, while good people do good.
Most people nowadays think that everyone is equally their neighbor and that they should be generous to anyone who is in need. It is a matter of Christian prudence, though, to check carefully what a person’s life is like and to extend goodwill accordingly. When we are devoted to the inner church we do this discriminatingly and therefore intelligently; but when we are devoted to the outer church we act indiscriminately because we are not capable of making distinctions like this.
The different kinds of neighbor that church people really should be aware of depend on the good that any particular individual is engaged in. Since everything good comes from the Lord, the Lord is our neighbor in the highest sense and to the utmost degree, the neighbor as the source [of all good]. It therefore follows that people are neighbors to us to the extent that they have the Lord in themselves; and since no two people accept the Lord (that is, the good that comes from him) in the same way, no two people are our neighbor in the same way. As to what is good, all the people in the heavens and all good people on earth are different. It never happens that exactly the same goodness is found in any two individuals. The goodness needs to vary so that each kind of goodness can stand on its own.
However, none of us can know all these distinctions and all the consequent distinct kinds of neighbor that arise in accordance with the different ways the Lord is accepted—that is, the way the good from him is accepted. Not even angels can know this except in a general way, by categories and their subcategories; and all the Lord requires of us in the church is that we live by what we know.
Since the goodness in every individual is different, it follows that the nature of each person’s goodness determines both the extent to which and the sense in which that individual can function as a neighbor to anyone else. We can see that this is the case from the Lord’s parable about the man who fell among thieves, whom both the priest and the Levite passed by, leaving him half dead, while the Samaritan, after he had bound up the man’s wounds and poured on oil and wine, lifted him onto his own beast and brought him to the inn and made arrangements for his care. This Samaritan is called “a neighbor” because he put into practice the goodness that is associated with goodwill (Luke 10:29–37). We may know from this that a neighbor is someone who is engaged in doing what is good. The oil and wine that the Samaritan poured into the wounds also mean what is good and the truth that it shows us.
from Regeneration, Pages 9, 10