“love” here is understood, rather, as “willing the good of another. In other words the willing of their ultimate good the ends to which man is ordered, the Beatific Vision(salvation). From this, the command to love our enemies by willing their good emerges, not as a harmful and self-flagellating defeatism.
(II-II, q. 25, a. 8), Aquinas argues that charity extends to all people, including enemies, because all are neighbors in the sense of being created by God and capable of eternal happiness.
However, Aquinas makes distinctions in how love is expressed. In the same question (I-II,q. 25, a. 9), he notes that loving an enemy does not mean approving of their unjust actions or refraining from resisting their evil. For instance, he supports the idea that justice can require punishment or defense against enemies, particularly in cases of harm to the common good, as seen in his discussion of just war.
In Aquinas’ Commentary on the Gospel of Matthew (Matt 5:44), Aquinas emphasizes that Christ’s command is about some warm fuzzy funny feelings, but an internal disposition of loving enemies in the sense of desiring their good and salvation, and not about maintaining personal affection or forgoing justice.
Concerning his commentary on Matthew; Aquinas writes: “according to Augustine, that we should, as to nature but not as to fault. Hence your adversary is to be loved in what he shares with you, as also appears among natural things; for white is opposed to black as it is unlike: as black, not as a color. Hence we should destroy hatred, i.e., the fact that he is an enemy should displease us, and we should destroy this in him.”
“And it should be known that to love someone is to will him good. But there are two kinds of good: eternal life, and charity intends this, because I am bound to love my neighbor as myself for eternal life; the other is temporal, and in this I am not bound to love my neighbor except insofar as these things lead to eternal life. Hence while preserving charity I can wish some temporal evil on my neighbor to the extent that it would give him the occasion of doing good and attaining eternal life.”
“Hence Gregory says in his Morals that the sign that you do not love your neighbor is when you rejoice in his ruin; but I can rejoice in his temporal ruin to the extent that it is ordered to his good or that of others or of the multitude.”
Concerning ST ll-ll 25 a6
“The prophet hated the unjust, as such, and the object of his hate was their injustice, which was their evil. Such hatred is perfect, of which he himself says (Psalm 138:22): "I have hated them with a perfect hatred." Now hatred of a person's evil is equivalent to love of his good. Hence also this perfect hatred belongs to charity.”
