I love George MacDonald, and in reading C.S. Lewis’s The Four Loves, I discovered references to his thoughts on love. Here is one paragraph of a lengthy excursus on both the impossibility and possibility of loving enemies. Sorry, it’s in King James English, and I don’t really have time to translate, but if you keep at it, you’ll get his point.
“Is it then reasonable to love our enemies? God does; therefore it must be the highest reason. But is it reasonable to expect that man should become capable of doing so? Yes; on one ground: that the divine energy is at work in man, to render at length man’s doing divine as his nature is. For this our Lord prayed when he said: “That they all may be one, as thou, Father, art in me, and I in thee, that they also may be one in us.” Nothing could be less likely to human judgment: our Lord knows that one day it will come.”
“But in the working of the Divine Love upon the race, my enemy is doomed to cease to be my enemy, and to become my friend. One flash of truth towards me would destroy my enmity at once; one hearty confession of wrong, and our enmity passes away; from each comes forth the brother who was inside the enemy all the time. For this The Truth is at work. In the faith of this, let us love the enemy now, accepting God’s work in reversion, as it were; let us believe as seeing his yet invisible triumph, clasping and holding fast our brother, in defiance of the changeful wiles of the wicked enchantment which would persuade our eyes and hearts that he is not our brother, but some horrible thing, hateful and hating.”
If you want to plug away at the entirety, you can find it here. This is a great literary site btw: