Simple, by understanding that the devil exists and lives among us. The story goes that God cleaned the heavens first and soon he will clean the earth. To sucsessfully win any battle, you have to take stratigic places to attack better and win the war.
Yes, I've heard that answer before, and if it works for you, that's great. But my question was rhetorical. My point is that you look at the world from your own perspective, assume we see it the same way, then question how we can stand to live in it. The answer is that we look at the world from a different perspective. If I can understand that your perspective is different, can't you understand that mine is, too?
See, the whole CIA torturing the terrorists is out there now. I also believe the terrorists torture too, not to mention that they cut heads off.
Yes, I'm aware of both those facts. That doesn't mean that torture is more common now than it was thousands of years ago.