Objection 1. It would seem that we ought to love those who are better more than those who are more closely united to us. For that which is in no way hateful seems more lovable than that which is hateful for some reason: just as a thing is all the whiter for having less black mixed with it. Now those who are connected with us are hateful for some reason, according to Luke 14:26: "If any man come to Me, and hate not his father," etc. On the other hand good men are not hateful for any reason. Therefore it seems that we ought to love those who are better more than those who are more closely connected with us.
Objection 2. Further, by charity above all, man is likened to God. But God loves more the better man. Therefore man also, out of charity, ought to love the better man more than one who is more closely united to him.
Objection 3. Further, in every friendship that ought to be loved most which has most to do with the foundation of that friendship: for, by natural friendship we love most those who are connected with us by nature, our parents for instance, or our children. Now the friendship of charity is founded upon the fellowship of happiness, which has more to do with better men than with those who are more closely united to us. Therefore, out of charity, we ought to love better men more than those who are more closely connected with us.
On the contrary, It is written (1 Timothy 5:8): "If any man have not care of his own and especially of those of his house, he hath denied the faith, and is worse than an infidel." Now the inward affection of charity ought to correspond to the outward effect. Therefore charity regards those who are nearer to us before those who are better.
I answer that, Every act should be proportionate both to its object and to the agent. But from its object it takes its species, while, from the power of the agent it takes the mode of its intensity: thus movement has its species from the term to which it tends, while the intensity of its speed arises from the disposition of the thing moved and the power of the mover. Accordingly love takes its species from its object, but its intensity is due to the lover.
Now the object of charity's love is God, and man is the lover. Therefore the specific diversity of the love which is in accordance with charity, as regards the love of our neighbor, depends on his relation to God, so that, out of charity, we should wish a greater good to one who is nearer to God; for though the good which charity wishes to all, viz. everlasting happiness, is one in itself, yet it has various degrees according to various shares of happiness, and it belongs to charity to wish God's justice to be maintained, in accordance with which better men have a fuller share of happiness. And this regards the species of love; for there are different species of love according to the different goods that we wish for those whom we love.
On the other hand, the intensity of love is measured with regard to the man who loves, and accordingly man loves those who are more closely united to him, with more intense affection as to the good he wishes for them, than he loves those who are better as to the greater good he wishes for them.
Again a further difference must be observed here: for some neighbors are connected with us by their natural origin, a connection which cannot be severed, since that origin makes them to be what they are. But the goodness of virtue, wherein some are close to God, can come and go, increase and decrease, as was shown above (24, 4,10,11). Hence it is possible for one, out of charity, to wish this man who is more closely united to one, to be better than another, and so reach a higher degree of happiness.
Moreover there is yet another reason for which, out of charity, we love more those who are more nearly connected with us, since we love them in more ways. For, towards those who are not connected with us we have no other friendship than charity, whereas for those who are connected with us, we have certain other friendships, according to the way in which they are connected. Now since the good on which every other friendship of the virtuous is based, is directed, as to its end, to the good on which charity is based, it follows that charity commands each act of another friendship, even as the art which is about the end commands the art which is about the means. Consequently this very act of loving someone because he is akin or connected with us, or because he is a fellow-countryman or for any like reason that is referable to the end of charity, can be commanded by charity, so that, out of charity both eliciting and commanding, we love in more ways those who are more nearly connected with us.
Reply to Objection 1. We are commanded to hate, in our kindred, not their kinship, but only the fact of their being an obstacle between us and God. In this respect they are not akin but hostile to us, according to Micah 7:6: "A men's enemies are they of his own household."
Reply to Objection 2. Charity conforms man to God proportionately, by making man comport himself towards what is his, as God does towards what is His. For we may, out of charity, will certain things as becoming to us which God does not will, because it becomes Him not to will them, as stated above (I-II, 19, 10), when we were treating of the goodness of the will.
Reply to Objection 3. Charity elicits the act of love not only as regards the object, but also as regards the lover, as stated above. The result is that the man who is more nearly united to us is more loved.
Source: Summa Theologica (New Advent)