Humans have tremendous capacity for good and evil.
The good is so simple, I think, that we too often fail to make it real.
“Imagine there’s no countries/ It isn’t hard to do/ Nothing to kill or die for/ And no religion too.”
The great paradox is that human evil is almost never that simply, yet we respond over and over to evil as if it is.
Addressing recent acts of terror in Beirut and Paris, Sunny Hundal writes that terrorists “want us to brush away humanity and compassion with suspicion and division,” adding: “By following that script we do exactly what Isis want us to do.”
Who we are must not be defined by those who choose evil, by that which is done to us.
Who we are must be defined by what we choose to do in the aftermath of evil.
Who we are must be defined by what we choose to recognize as terror and evil, as well. Our selective and narrow gaze of outrage is another kind of evil—one that renders some inhuman by our indifference—that lies at our feet even as we condemn large-scale brazen evil.
We must not allow the din of sword rattling to drown out the voices of the past that may, again, seem to be too simple:
“An eye for an eye leaves the whole world blind.” 
Let us move now from the practical how to the theoretical why: Why should we love our enemies? The first reason is fairly obvious. Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness; only light can do that. Hate cannot drive out hate; only love can do that. Hate multiplies hate, violence multiplies violence, and toughness multiplies toughness in a descending spiral of destruction. (Martin Luther King Jr., Loving Your Enemies) 
 Attributed to Gandhi, but never confirmed as an accurate attribution.
 See how even accurate attributions can be manipulated here.