Can you have an enemy, when the enemy doesn't know it? Can you have an enemy, when you don't know it?
The enemy that seeks your life is one kind of enemy, but it is largely the creation of the entertainment industry. Few of us have someone dedicated to taking our life. Most murders occur between friends, not strangers. Most victims of violent crime know their assailants. Strangers lurking in the bushes are a frightening idea, but they are seldom reality. And an enemy doesn't always seek to do you violence.
Facing the stone cold heartlessness of the other is like facing an open pit. How to not fall in? How to face that emptiness without needing to summon all your own ego in hating that person just to know that sense of "I AM." Hating is easier than facing the void. And loving, pouring love into a bottomless pit...isn't that somehow what God did when he loved us into being, into creation?
How not to fall in, indeed. And why the need to fall in, except the "enemy" challenges the "boundaries" that you have declared to be your "self." And defending the boundaries of the self is always a losing proposition. So let it go; it is lost. Hold fast to the center. And consider: how can you have an "enemy" whom you do not see face to face, even "the stone cold heartless" face? How can you have an enemy who does not know you, as you know your enemy? How can the relationship of "enemy" not be reciprocal?
These are not abstract questions of the philosophy of religion. These are the necessary fundamentals, the "building blocks" toward understanding how one can "love" one's "enemy"?