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 in basically the same manner indiscriminately–just as much to evil people as 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 out church we act indiscriminately because we are 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 deeds to vary so that each kind of goodness can stand on its own.
from Regeneration, Page 9